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Aerospace
Volume 9
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Aerospace, Volume 9, Issue 2 (February 2022) – 70 articles

Cover Story (view full-size image): Small satellites and CubeSats are experiencing increasing interest from the space community, because of the performance available with current technologies at a reduced cost with respect to larger spacecraft. Notably, the hardware composing the attitude and orbit control systems has reached a strong maturity level, and the dimensions of the components allow redundant sets of sensors and actuators. Thus, the software shall be able to handle these redundancies with a fault-tolerant structure. This research work develops an attitude and orbit determination system with embedded failure detection and isolation functions, and autonomous redundant component management for on-board failure recovery. The system is sized for small satellites, characterized by very limited computing power. View this paper
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27 pages, 6048 KiB  
Article
An Optimal Fuzzy Logic-Based Energy Management Strategy for a Fuel Cell/Battery Hybrid Power Unmanned Aerial Vehicle
by Tao Lei, Yanbo Wang, Xianqiu Jin, Zhihao Min, Xingyu Zhang and Xiaobin Zhang
Aerospace 2022, 9(2), 115; https://doi.org/10.3390/aerospace9020115 - 21 Feb 2022
Cited by 26 | Viewed by 4581
Abstract
With the development of high-altitude and long-endurance unmanned aerial vehicles (UAVs), optimization of the coordinated energy dispatch of UAVs’ energy management systems has become a key target in the research of electric UAVs. Several different energy management strategies are proposed herein for improving [...] Read more.
With the development of high-altitude and long-endurance unmanned aerial vehicles (UAVs), optimization of the coordinated energy dispatch of UAVs’ energy management systems has become a key target in the research of electric UAVs. Several different energy management strategies are proposed herein for improving the overall efficiency and fuel economy of fuel cell/battery hybrid electric power systems (HEPS) of UAVs. A rule-based (RB) energy management strategy is designed as a baseline for comparison with other strategies. An energy management strategy (EMS) based on fuzzy logic (FL) for HEPS is presented. Compared with classical rule-based strategies, the fuzzy logic control has better robustness to power fluctuations in the UAV. However, the proposed FL strategy has an inherent defect: the optimization performances will be determined by the heuristic method and the past experiences of designers to a great extent rather than a specific cost function of the algorithm itself. Thus, the paper puts forward an improved fuzzy logic-based strategy that uses particle swarm optimization (PSO) to track the optimal thresholds of membership functions, and the equivalent hydrogen consumption minimization is considered as the objective function. Using a typical 30 min UAV mission profile, all the proposed EMS were verified by simulations and rapid controller prototype (RCP) experiments. Comprehensive comparisons and analysis are presented by evaluating hydrogen consumption, system efficiency and voltage bus stability. The results show that the PSO-FL algorithm can further improve fuel economy and achieve superior overall dynamic performance when controlling a UAV’s fuel-cell powertrain. Full article
(This article belongs to the Special Issue Fuel Cell Aircraft)
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19 pages, 6856 KiB  
Article
Simulation of Runway Irregularities in a Novel Test Rig for Fully Electrical Landing Gear Systems
by Andrea De Martin, Giovanni Jacazio and Massimo Sorli
Aerospace 2022, 9(2), 114; https://doi.org/10.3390/aerospace9020114 - 21 Feb 2022
Cited by 5 | Viewed by 3142
Abstract
The E-LISA research project, under way within the Clean Sky 2 framework, has the objective of developing an innovative iron bird dedicated to executing tests on the landing gear of a small aircraft transport equipped with an electro-mechanical landing gear and electrical brake. [...] Read more.
The E-LISA research project, under way within the Clean Sky 2 framework, has the objective of developing an innovative iron bird dedicated to executing tests on the landing gear of a small aircraft transport equipped with an electro-mechanical landing gear and electrical brake. Such tests include the simulation of complete landing procedures under different operating conditions such as runway friction, presence of periodical defects along the runway, variable aircraft weight, and approach speed. To this end, the iron bird requires novel solutions in both its architecture and its control scheme. This paper details an innovative solution that is being implemented in the E-LISA iron bird to enable the execution of tests on a landing gear, reproducing the effects of any type of runway irregularity. First, the rig architecture is presented in detail, with particular care toward the hybrid position/force control system that manages its operations. Then, a simulation model is introduced with the objective of verifying the control system stability and the test rig capability to reproduce on the test articles the effects produced on the landing gear leg of periodical runway irregularities. Simulations results are presented, highlighting the stability of the proposed control scheme and providing a preliminary assessment of the system performances. Full article
(This article belongs to the Special Issue 11th EASN International Conference on Innovation in Aviation & Space to the Satisfaction of the European Citizens)
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21 pages, 10509 KiB  
Article
Design and Simulation Analysis of an Electromagnetic Damper for Reducing Shimmy in Electrically Actuated Nose Wheel Steering Systems
by Chenfei She, Ming Zhang, Yibo Ge, Liming Tang, Haifeng Yin and Gang Peng
Aerospace 2022, 9(2), 113; https://doi.org/10.3390/aerospace9020113 - 19 Feb 2022
Cited by 3 | Viewed by 3578
Abstract
Based on the technical platform of electrically actuated nose wheel steering systems, a new type of damping shimmy reduction technology is developed to break through the limitations of traditional hydraulic damping shimmy reduction methods, and an electrically actuated nose wheel steering structure scheme [...] Read more.
Based on the technical platform of electrically actuated nose wheel steering systems, a new type of damping shimmy reduction technology is developed to break through the limitations of traditional hydraulic damping shimmy reduction methods, and an electrically actuated nose wheel steering structure scheme is proposed. The mathematical model of the electromagnetic damper is established, the derivation of skin depth, damping torque and damping coefficient is completed, and the design of the shape and size of the electromagnetic damper is combined with the derivation results and the technical index of shimmy reduction. The electromagnetic field finite element simulation results show that the mathematical modeling method of the electromagnetic damper has good accuracy, and its application to the shimmy reduction module of the electrically actuated nose wheel steering system is also feasible and superior. Finally, the key factors influencing the performance of electromagnetic damper shimmy reduction are studied and analyzed, thus forming a complete electromagnetic damper shimmy reduction technology for the electrically actuated system, and laying the foundation for the design of novel all-electric aircraft and landing gear. Full article
(This article belongs to the Special Issue Electro-Mechanical Actuators for Safety-Critical Aerospace Applications)
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21 pages, 3417 KiB  
Article
Effectiveness of Conflict Resolution Methods in Air Traffic Management
by Anrieta Dudoit, Vytautas Rimša, Marijonas Bogdevičius and Jacek Skorupski
Aerospace 2022, 9(2), 112; https://doi.org/10.3390/aerospace9020112 - 19 Feb 2022
Cited by 5 | Viewed by 4722
Abstract
Aircraft fly en route under concurrent event situations (conflicting situations), which occur when they operate in the same airspace but are too close to each other in the same time frame. Hence, the safe horizontal distance between them is not less than the [...] Read more.
Aircraft fly en route under concurrent event situations (conflicting situations), which occur when they operate in the same airspace but are too close to each other in the same time frame. Hence, the safe horizontal distance between them is not less than the standard 5 nm. Free route airspace is such a concept, where such concurrent events need to be resolved when the location and number of such event “hotspots” are random in comparison with fixed route (conventional) airspace. This paper proposes two approaches to solving the traffic conflict in the sector by performing horizontal resolution maneuvers. The first of them uses the Dubins trajectory, while the second one uses a three-fold change of heading (3HC) method (for two types of angles). Apart from maintaining safe separation, we compared them, taking as a criterion the extension of the flight path of aircraft involved in the conflict, as the length of the flight is the primary factor determining flight time/delays and the increase in fuel consumption and greenhouse gas emissions. There may be other algorithms depending on the different data that can be identified through further research. Full article
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11 pages, 5450 KiB  
Article
Pre-Flight Test Verification of Automatic Stabilization System Using Aircraft Trimming Surfaces
by Albert Zajdel, Mariusz Krawczyk and Cezary Szczepański
Aerospace 2022, 9(2), 111; https://doi.org/10.3390/aerospace9020111 - 19 Feb 2022
Cited by 5 | Viewed by 3181
Abstract
The new requirement of installing the flight stabilization system onboard the airplanes for performing the single-pilot flights in IFR rules was issued lately. It caused the necessity of developing such a system for small aircraft. The proposed system was developed using Model-Based Design [...] Read more.
The new requirement of installing the flight stabilization system onboard the airplanes for performing the single-pilot flights in IFR rules was issued lately. It caused the necessity of developing such a system for small aircraft. The proposed system was developed using Model-Based Design then tuned and tested in Model, Pilot and Hardware in the Loop Simulations. The paper presents the next advanced stage of testing—verification in simulation and ground tests on the PZL-130 Orlik airplane. The implementation of this system does not modify the pilot’s primary manual controls. The newly introduced electrical trim is used for automatic stabilization but can be used at manual trimming as it was previously, depending on the chosen operation mode. The ground tests were planned according to civil aviation authority and aviation law requirements. Chosen results from simulated flights were analyzed and presented, confirming the effectiveness of the proposed system. The dedicated application allowing the test engineer to change stabilization system parameters during the flight on a touchscreen tablet was developed and described. The outcome of the stabilization system test campaign was a verification of its performance before the flight tests. The comparison of simulated and real flight data will allow identifying model deficiencies and flight stabilization system efficiency, which makes possible improvements implementation. Additionally, it appeared to be the cost-effective and less electrical energy-consuming automatic flight stabilization system for small aircraft. Such features benefit initiatives like Future Sky, More Electric Aircraft and aircraft stabilization system retrofit. Full article
(This article belongs to the Special Issue 11th EASN International Conference on Innovation in Aviation & Space to the Satisfaction of the European Citizens)
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35 pages, 11995 KiB  
Article
Lessons Learned from IDEASSat: Design, Testing, on Orbit Operations, and Anomaly Analysis of a First University CubeSat Intended for Ionospheric Science
by Yi-Chung Chiu, Loren C. Chang, Chi-Kuang Chao, Tzu-Ya Tai, Kai-Lun Cheng, Hsin-Tzu Liu, Rong Tsai-Lin, Chi-Ting Liao, Wei-Hao Luo, Guan-Po Chiu, Kai-Jie Hou, Ruo-Yu Wang, Glenn Franco Gacal, Pin-An Lin, Sittinat Denduonghatai, Tsai-Ru Yu, Jann-Yenq Liu, Amal Chandran, Kashyapa Bramha Naren Athreyas, Priyadarshan Hari, Joji John Varghese and Mustapha Meftahadd Show full author list remove Hide full author list
Aerospace 2022, 9(2), 110; https://doi.org/10.3390/aerospace9020110 - 18 Feb 2022
Cited by 5 | Viewed by 4820
Abstract
Given the pervasive use of satellite and over the horizon wireless communication technology in modern society, ionospheric disturbances that can disrupt such services are a crucial consideration. Ionospheric irregularities, plasma bubbles and other phenomena can have a great impact on satellite navigation and [...] Read more.
Given the pervasive use of satellite and over the horizon wireless communication technology in modern society, ionospheric disturbances that can disrupt such services are a crucial consideration. Ionospheric irregularities, plasma bubbles and other phenomena can have a great impact on satellite navigation and communications, impacting other systems reliant on such technologies. The Ionospheric Dynamics and Attitude Subsystem Satellite (IDEASSat) was a 3U developed by National Central University (NCU) to measure irregularities in the ionosphere, as well as to establish spacecraft engineering and operations capacity at NCU. The onboard Compact Ionospheric Probe (CIP) could measure high-resolution plasma parameters, which can be used for identifying ionospheric irregularities that can cause scintillation in satellite navigation and communications signals. Part of the spacecraft sub-systems were independently designed and developed by students, who were also responsible for integration, testing, and operations. IDEASSat was successfully launched into low Earth orbit on 24 January 2021, and then began mission operations. The spacecraft successfully demonstrated three-axis attitude stabilization and control, tracking, telemetry and command (TT&C), as well as flight software and ground systems that could support autonomous operation. The spacecraft experienced a critical anomaly 22 days after launch, followed by a 1.5-month communications blackout. The spacecraft briefly recovered from the blackout for long enough to replay flight data, which allowed for the cause of the blackout to be determined as an inability of the electrical power subsystem reset circuit to recover from an ionizing radiation induced single event latch-up. Although the mission was not completed, flight data obtained during the mission will help to improve the designs of future spacecraft in development at NCU. This paper will introduce IDEASSat’s final flight model design and implementation, integration, testing, environmental verification, and failure analysis, and will review the performance of the spacecraft during on-orbit operations. The results and experiences encountered in implementation and operations of the IDEASSat mission are presented here as a reference for other university small satellite teams. Full article
(This article belongs to the Section Astronautics & Space Science)
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23 pages, 6134 KiB  
Article
Fundamental Framework to Plan 4D Robust Descent Trajectories for Uncertainties in Weather Prediction
by Shumpei Kamo, Judith Rosenow, Hartmut Fricke and Manuel Soler
Aerospace 2022, 9(2), 109; https://doi.org/10.3390/aerospace9020109 - 17 Feb 2022
Cited by 4 | Viewed by 3444
Abstract
Aircraft trajectory planning is affected by various uncertainties. Among them, those in weather prediction have a large impact on the aircraft dynamics. Trajectory planning that assumes a deterministic weather scenario can cause significant performance degradation and constraint violation if the actual weather conditions [...] Read more.
Aircraft trajectory planning is affected by various uncertainties. Among them, those in weather prediction have a large impact on the aircraft dynamics. Trajectory planning that assumes a deterministic weather scenario can cause significant performance degradation and constraint violation if the actual weather conditions are significantly different from the assumed ones. The present study proposes a fundamental framework to plan four-dimensional optimal descent trajectories that are robust against uncertainties in weather-prediction data. To model the nature of the uncertainties, we utilize the Global Ensemble Forecast System, which provides a set of weather scenarios, also referred to as members. A robust trajectory planning problem is constructed based on the robust optimal control theory, which simultaneously considers a set of trajectories for each of the weather scenarios while minimizing the expected value of the overall operational costs. We validate the proposed planning algorithm with a numerical simulation, assuming an arrival route to Leipzig/Halle Airport in Germany. Comparison between the robust and the inappropriately-controlled trajectories shows the proposed robust planning strategy can prevent deteriorated costs and infeasible trajectories that violate operational constraints. The simulation results also confirm that the planning can deal with a wide range of cost-index and required-time-of-arrival settings, which help the operators to determine the best values for these parameters. The framework we propose is in a generic form, and therefore it can be applied to a wide range of scenario settings. Full article
(This article belongs to the Special Issue Closing the Gap in Aircraft Trajectories: Enhancing Optimization and Prediction Approaches)
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31 pages, 135826 KiB  
Article
Clap-and-Fling Mechanism in Non-Zero Inflow of a Tailless Two-Winged Flapping-Wing Micro Air Vehicle
by Loan Thi Kim Au, Hoon Cheol Park, Seok Tae Lee and Sung Kyung Hong
Aerospace 2022, 9(2), 108; https://doi.org/10.3390/aerospace9020108 - 16 Feb 2022
Cited by 5 | Viewed by 3745
Abstract
The aerodynamic performance of clap-and-fling mechanism in a KU-Beetle—a tailless two-winged flapping-wing micro air vehicle—was investigated for various horizontal free-stream inflows. Three inflow speeds of 0 (hovering), 2.52 m/s and 5.04 m/s corresponding to advance ratios of 0, 0.5 and 1 were considered. [...] Read more.
The aerodynamic performance of clap-and-fling mechanism in a KU-Beetle—a tailless two-winged flapping-wing micro air vehicle—was investigated for various horizontal free-stream inflows. Three inflow speeds of 0 (hovering), 2.52 m/s and 5.04 m/s corresponding to advance ratios of 0, 0.5 and 1 were considered. The forces and moments for two wing distances of 16 mm (in which the clap-and-fling effect was strong) and 40 mm (in which the clap-and-fling effect was diminished) were computed using commercial software of ANSYS-Fluent 16.2. When the advance ratio increased from 0 to 0.5 and 1, the lift enhancement due to clap in the down-stroke reversal increased from 1.1% to 1.7% and 1.9%, while that in the up-stroke reversal decreased from 2.1% to −0.5% and 1.1%. Thus, in terms of lift enhancement due to clap, the free-stream inflow was more favorable in the down stroke than the up stroke. For all investigated inflow speeds, the clap-and-fling effect augmented the lift and power consumption but reduced the lift-to-power ratio. The total contributions of the fling phases to the enhancements in lift, torque, and power consumption were more than twice those of the clap phases. For the advance ratio from 0 to 0.5 and 1, the enhancement in average lift slightly decreased from 9.9% to 9.4% and 9.1%, respectively, and the augmentation in average power consumption decreased from 12.3% to 10.5% and 9.7%. Meanwhile, the reduction in the average lift-to-power ratio decreased from 2.1% to 1.1% and 0.6%, implying that in terms of aerodynamic efficiency, the free-stream inflow benefits the clap-and-fling effect in the KU-Beetle. Full article
(This article belongs to the Special Issue Bioinspired Flying Systems)
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13 pages, 3672 KiB  
Article
Electro-Thermal Parameters of Graphene Nano-Platelets Films for De-Icing Applications
by Khitem Lahbacha, Sarah Sibilia, Gianmarco Trezza, Gaspare Giovinco, Francesco Bertocchi, Sergio Chiodini, Francesco Cristiano and Antonio Maffucci
Aerospace 2022, 9(2), 107; https://doi.org/10.3390/aerospace9020107 - 16 Feb 2022
Cited by 6 | Viewed by 2499
Abstract
This paper provides a study of some relevant electro-thermal properties of commercial films made by pressed graphene nano-platelets (GNPs), in view of their use as heating elements in innovative de-icing systems for aerospace applications. The equivalent electrical resistivity and thermal emissivity were studied, [...] Read more.
This paper provides a study of some relevant electro-thermal properties of commercial films made by pressed graphene nano-platelets (GNPs), in view of their use as heating elements in innovative de-icing systems for aerospace applications. The equivalent electrical resistivity and thermal emissivity were studied, by means of models and experimental characterization. Macroscopic strips with a length on the order of tens of centimeters were analyzed, either made by pure GNPs or by composite mixtures of GNPs and a small percentage of polymeric binders. Analytical models are derived and experimentally validated. The thermal response of these graphene films when acting as a heating element is studied and discussed. Full article
(This article belongs to the Special Issue 11th EASN International Conference on Innovation in Aviation & Space to the Satisfaction of the European Citizens)
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25 pages, 8011 KiB  
Article
Influence of Blade Fracture on the Flow of Rotor-Stator Systems with Centrifugal Superposed Flow
by Gang Zhao, Tian Qiu and Peng Liu
Aerospace 2022, 9(2), 106; https://doi.org/10.3390/aerospace9020106 - 16 Feb 2022
Cited by 4 | Viewed by 2225
Abstract
Rotor-stator cavities are often found in turbomachinery; they supply cold air that is bled from the compressor to the turbine blades. The pressure of the outlet of a rotor-stator cavity is axisymmetric under normal circumstances. However, its pressure would be non-axisymmetric in the [...] Read more.
Rotor-stator cavities are often found in turbomachinery; they supply cold air that is bled from the compressor to the turbine blades. The pressure of the outlet of a rotor-stator cavity is axisymmetric under normal circumstances. However, its pressure would be non-axisymmetric in the event of blade fracture. The impact of blade fracture on a rotor-stator cavity with centrifugal superposed flow is studied in this paper. The Euler number E, the rotational Reynolds number Reφ, and the low-pressure zone range θ are investigated and, for the first time, with the non-axisymmetrical boundary conditions employing numerical simulation. The results of the numerical calculations show that after turbine blade fracture, the velocity is more affected in the downstream region at a high radius, especially when the Reφ is large. As for the distribution of the mass flow rate, there may be a critical θc at which the other blades are least affected. The θc would increase as the Reφ or the E increase, and the θc≅0.2 when Cw=10,137, Reφ=5.12×105, and 0.2≤E≤0.4. In addition, the thrust coefficient increases as the E or the θ increases, and the increase in the thrust coefficient does not exceed 4% when the E=0.2 and the θ=0.1 in this paper. However, the moment coefficient on the rotating shaft is almost independent of the E and the θ. An increase in the Reφ will reduce the effect of turbine blade fracture on the thrust and moment coefficients, when the Reφ is small. Full article
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16 pages, 4126 KiB  
Article
TDE-Based Adaptive Integral Sliding Mode Control of Space Manipulator for Space-Debris Active Removal
by Zhibin Zhang, Xinhong Li, Xun Wang, Xin Zhou, Jiping An and Yanyan Li
Aerospace 2022, 9(2), 105; https://doi.org/10.3390/aerospace9020105 - 16 Feb 2022
Cited by 10 | Viewed by 3022
Abstract
The safe and dependable removal of large-scale space debris has been a long-standing challenge that is critical to the safety of spacecraft and astronauts. In the process of capturing and deorbiting space debris, the space manipulator must achieve extremely high control and precision. [...] Read more.
The safe and dependable removal of large-scale space debris has been a long-standing challenge that is critical to the safety of spacecraft and astronauts. In the process of capturing and deorbiting space debris, the space manipulator must achieve extremely high control and precision. However, strong couplings, model uncertainties, and various inevitable unknown disturbances cause many difficulties in coordinated control of the space manipulator. To solve this challenge, this study examines the stabilization control of a space manipulator after capturing non-cooperative large-scale space debris and presents an adaptive integral sliding mode control (AISMC) scheme with time-delay estimation (TDE). The coupling term and lumped uncertainty are estimated by TDE technology, which eliminates the requirement of prior knowledge. Adaptive sliding mode control (ASMC) is used as desired injecting dynamics to compensate TDE errors, and a PID-type integral sliding mode surface is designed to reduce steady-state errors. The Lyapunov criterion is used to prove the global stability of the controller. Simulation results show that the controller has high tracking accuracy and strong robustness. Full article
(This article belongs to the Special Issue Space Debris Removal: Challenges and Opportunities)
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21 pages, 571 KiB  
Article
Parameter-Matching Algorithm and Optimization of Integrated Thermal Management System of Aircraft
by Ri Wang, Sujun Dong, Hongsheng Jiang, Peiru Li and Hainan Zhang
Aerospace 2022, 9(2), 104; https://doi.org/10.3390/aerospace9020104 - 15 Feb 2022
Cited by 9 | Viewed by 2691
Abstract
The integrated thermal management system of aircraft is essential to maintain a suitable environment for the cabin crew and devices. The system is composed of the air-cycle refrigeration subsystem, the vapor-compression refrigeration subsystem, the liquid-cooling subsystem and the fuel-cycle subsystem, which are coupled [...] Read more.
The integrated thermal management system of aircraft is essential to maintain a suitable environment for the cabin crew and devices. The system is composed of the air-cycle refrigeration subsystem, the vapor-compression refrigeration subsystem, the liquid-cooling subsystem and the fuel-cycle subsystem, which are coupled with each other through heat exchangers. Due to the complex structure and large number of components in the system, it is necessary to design a corresponding parameter-matching algorithm for its special structure and to select the appropriate optimization design method. In this paper, the structure of an integrated thermal management system is analyzed in depth. A hierarchical matching algorithm of system parameters was designed and realized. Meanwhile, a sensitivity analysis of the system was performed, where key parameters were selected. Besides, a variety of optimization algorithms was used to optimize the design calculations. The results show that the particle swarm optimization and genetic algorithm could effectively find the global optimal solution when taking the fuel penalty as the objective function. Furthermore, the particle swarm optimization method took less time. Full article
(This article belongs to the Section Aeronautics)
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42 pages, 9484 KiB  
Article
Atmospheric Disturbance Modelling for a Piloted Flight Simulation Study of Airplane Safety Envelope over Complex Terrain
by Xinying Liu, Anna Abà, Pierluigi Capone, Leonardo Manfriani and Yongling Fu
Aerospace 2022, 9(2), 103; https://doi.org/10.3390/aerospace9020103 - 14 Feb 2022
Cited by 5 | Viewed by 5048
Abstract
A concept of a new energy management system synthesizing meteorological and orographic influences on airplane safety envelope was developed and implemented at the ZHAW Centre for Aviation. A corresponding flight simulation environment was built in a Research and Didactics Simulator (ReDSim) to test [...] Read more.
A concept of a new energy management system synthesizing meteorological and orographic influences on airplane safety envelope was developed and implemented at the ZHAW Centre for Aviation. A corresponding flight simulation environment was built in a Research and Didactics Simulator (ReDSim) to test the first implementation of the cockpit display system. A series of pilot-in-the-loop flight simulations were carried out with a group of pilots. A general aviation airplane model Piper PA-28 was modified for the study. The environment model in the ReDSim was modified to include a new ad hoc subsystem simulating atmospheric disturbance. In order to generate highly resolved wind fields in the ReDsim, a well-established large-eddy simulation model, the Parallelized Large-Eddy Simulation (PALM) framework, was used in the concept study, focusing on a small mountainous region in Switzerland, not far from Samedan. For a more realistic representation of specific meteorological situations, PALM was driven with boundary conditions extracted from the COSMO-1 reanalysis of MeteoSwiss. The essential variables (wind components, temperature, and pressure) were extracted from the PALM output and fed into the subsystem after interpolation to obtain the values at any instant and any aircraft position. Within this subsystem, it is also possible to generate statistical atmospheric turbulence based on the widely used Dryden turbulence model. The paper compares two ways of generating atmospheric turbulence, by combining the numerical method with the statistical model and introduces the flight test procedure with an emphasis on turbulence realism; it then presents the experiment results including a statistical assessment achieved by collecting pilot feedback on turbulence characteristics and turbulence/task combination. Full article
(This article belongs to the Special Issue Aircraft Modeling for Design, Simulation and Control)
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18 pages, 1363 KiB  
Article
A Robust Reacting Flow Solver with Computational Diagnostics Based on OpenFOAM and Cantera
by Dezhi Zhou, Hongyuan Zhang and Suo Yang
Aerospace 2022, 9(2), 102; https://doi.org/10.3390/aerospace9020102 - 14 Feb 2022
Cited by 14 | Viewed by 5966
Abstract
In this study, we developed a new reacting flow solver based on OpenFOAM (OF) and Cantera, with the capabilities of (i) dealing with detailed species transport and chemistry, (ii) integration using a well-balanced splitting scheme, and (iii) two advanced computational diagnostic methods. First [...] Read more.
In this study, we developed a new reacting flow solver based on OpenFOAM (OF) and Cantera, with the capabilities of (i) dealing with detailed species transport and chemistry, (ii) integration using a well-balanced splitting scheme, and (iii) two advanced computational diagnostic methods. First of all, a flaw of the original OF chemistry model to deal with pressure-dependent reactions is fixed. This solver then couples Cantera with OF so that the robust chemistry reader, chemical reaction rate calculations, ordinary differential equations (ODEs) solver, and species transport properties handled by Cantera can be accessed by OF. In this way, two transport models (mixture-averaged and constant Lewis number models) are implemented in the coupled solver. Finally, both the Strang splitting scheme and a well-balanced splitting scheme are implemented in this solver. The newly added features are then assessed and validated via a series of auto-ignition tests, a perfectly stirred reactor, a 1D unstretched laminar premixed flame, a 2D counter-flow laminar diffusion flame, and a 3D turbulent partially premixed flame (Sandia Flame D). It is shown that the well-balanced property is crucial for splitting schemes to accurately capture the ignition and extinction events. To facilitate the understanding on combustion modes and complex chemistry in large scale simulations, two computational diagnostic methods (conservative chemical explosive mode analysis, CCEMA, and global pathway analysis, GPA) are subsequently implemented in the current framework and used to study Sandia Flame D for the first time. It is shown that these two diagnostic methods can extract the flame structure, combustion modes, and controlling global reaction pathways from the simulation data. Full article
(This article belongs to the Section Aeronautics)
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17 pages, 8282 KiB  
Article
Fast Path Planning for Long-Range Planetary Roving Based on a Hierarchical Framework and Deep Reinforcement Learning
by Ruijun Hu and Yulin Zhang
Aerospace 2022, 9(2), 101; https://doi.org/10.3390/aerospace9020101 - 14 Feb 2022
Cited by 16 | Viewed by 3165
Abstract
The global path planning of planetary surface rovers is crucial for optimizing exploration benefits and system safety. For the cases of long-range roving or obstacle constraints that are time-varied, there is an urgent need to improve the computational efficiency of path planning. This [...] Read more.
The global path planning of planetary surface rovers is crucial for optimizing exploration benefits and system safety. For the cases of long-range roving or obstacle constraints that are time-varied, there is an urgent need to improve the computational efficiency of path planning. This paper proposes a learning-based global path planning method that outperforms conventional searching and sampling-based methods in terms of planning speed. First, a distinguishable feature map is constructed through a traversability analysis of the extraterrestrial digital elevation model. Then, considering planning efficiency and adaptability, a hierarchical framework consisting of step iteration and block iteration is designed. For the planning of each step, an end-to-end step planner named SP-ResNet is proposed that is based on deep reinforcement learning. This step planner employs a double-branch residual network for action value estimation, and is trained over a simulated DEM map collection. Comparative analyses with baselines demonstrate the prominent advantage of our method in terms of planning speed. Finally, the method is verified to be effective on real lunar terrains using CE2TMap2015. Full article
(This article belongs to the Special Issue AI/Machine Learning in Aerospace Autonomy)
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28 pages, 16151 KiB  
Article
Mission Test Campaign for the EIRSAT-1 Engineering Qualification Model
by Maeve Doyle, Rachel Dunwoody, Gabriel Finneran, David Murphy, Jack Reilly, Joseph Thompson, Sai Krishna Reddy Akarapu, Joseph Mangan, Sarah Walsh, Jessica Erkal, Fergal Marshall, Lána Salmon, Eoghan Somers, Lily Ha, David Palma, Antonio Martin-Carrillo, Sheila McBreen, David McKeown, William O’Connor, Brian Shortt, Alexey Uliyanov, Ronan Wall and Lorraine Hanlonadd Show full author list remove Hide full author list
Aerospace 2022, 9(2), 100; https://doi.org/10.3390/aerospace9020100 - 13 Feb 2022
Cited by 5 | Viewed by 4415
Abstract
The compact, standardised form factor of CubeSats allows for the use of commercial off-the-shelf components, reducing traditional barriers to entry, such as cost and development time. More than 1500 of these small spacecraft have been launched in the past 20 years, with improving [...] Read more.
The compact, standardised form factor of CubeSats allows for the use of commercial off-the-shelf components, reducing traditional barriers to entry, such as cost and development time. More than 1500 of these small spacecraft have been launched in the past 20 years, with improving capabilities that enable a wide range of mission profiles. The Educational Irish Research Satellite, EIRSAT-1, is a CubeSat being developed by a student-led team with goals that span education, technology demonstration and science. A comprehensive mission test plan, in which in-flight conditions are simulated, has been developed for EIRSAT-1 and implemented using an engineering qualification model of the spacecraft. In addition to verifying 41 mission requirements, the successful execution of the mission test plan established that the full satellite system can perform the intended mission. Mission testing also proved to be an invaluable tool to prepare for launch and operations, providing the team with a more complete understanding of the satellite’s expected on-orbit behaviour. This work presents a detailed description of the mission test planning process and implementation, as well as key results and lessons learned. In doing so, this work aims to improve the on-orbit reliability of CubeSats by disseminating resources and good practice around mission testing. Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites II)
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30 pages, 4388 KiB  
Article
Thermal Vacuum Test Campaign of the EIRSAT-1 Engineering Qualification Model
by Rachel Dunwoody, Jack Reilly, David Murphy, Maeve Doyle, Joseph Thompson, Gabriel Finneran, Lána Salmon, Conor O’Toole, Sai Krishna Reddy Akarapu, Jessica Erkal, Joseph Mangan, Fergal Marshall, Eoghan Somers, Sarah Walsh, Daithí de Faoite, Mike Hibbett, David Palma, Loris Franchi, Lily Ha, Lorraine Hanlon, David McKeown, William O’Connor, Alexey Uliyanov, Ronan Wall, Brian Shortt and Sheila McBreenadd Show full author list remove Hide full author list
Aerospace 2022, 9(2), 99; https://doi.org/10.3390/aerospace9020099 - 12 Feb 2022
Cited by 9 | Viewed by 7601
Abstract
CubeSats facilitate rapid development and deployment of missions for educational, technology demonstration, and scientific purposes. However, they are subject to a high failure rate, with a leading cause being the lack of system-level verification. The Educational Irish Research Satellite (EIRSAT-1) is a CubeSat [...] Read more.
CubeSats facilitate rapid development and deployment of missions for educational, technology demonstration, and scientific purposes. However, they are subject to a high failure rate, with a leading cause being the lack of system-level verification. The Educational Irish Research Satellite (EIRSAT-1) is a CubeSat mission under development in the European Space Agency’s (ESA) Fly Your Satellite! Programme. EIRSAT-1 is a 2U CubeSat with three novel payloads and a bespoke antenna deployment module, which all contribute to the complexity of the project. To increase the likelihood of mission success, a prototype model philosophy is being employed, where both an engineering qualification model (EQM) and a flight model of EIRSAT-1 are being built. Following the assembly of the EQM, the spacecraft underwent a successful full functional test and month-long mission test. An environmental test campaign in ESA Education Office’s CubeSat Support Facility was then conducted with the EQM where both vibration and thermal verification test campaigns were performed. The focus of this paper is the thermal testing and verification of the EIRSAT-1 EQM. Over three weeks, the EQM was subjected to one non-operational cycle, three and a half operational cycles, and a thermal balance test in a thermal vacuum chamber. After dwelling at each temperature extreme, functional tests were performed to investigate the performance of the spacecraft in this space representative environment. The approach to planning and executing the thermal testing is described in detail including the documentation required, set up of the test equipment, and determination of the test levels. Overall, the campaign demonstrated that the mission can successfully operate in a space environment similar to that expected in orbit, despite encountering a number of issues. These issues included a payload displaying anomalous behaviour at cold temperatures and needing to redefine test levels due to an insufficient understanding of the internal dissipation in the spacecraft. A total of two major and three minor non-conformances were raised. Crucially, these issues could not have been found without thermal testing, despite the comprehensive ambient tests performed. The main results and lessons learned during this thermal test campaign are presented with the aim of guiding future missions on optimal approaches in organising and executing the thermal testing of their CubeSats. Full article
(This article belongs to the Special Issue Verification Approaches for Nano- and Micro-Satellites II)
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22 pages, 1307 KiB  
Article
Multi-Objective Comparative Analysis of Active Modular Rectifier Architectures for a More Electric Aircraft
by Unai Atutxa, Igor Baraia-Etxaburu, Víctor Manuel López, Fernando González-Hernando and Alejandro Rujas
Aerospace 2022, 9(2), 98; https://doi.org/10.3390/aerospace9020098 - 12 Feb 2022
Viewed by 3123
Abstract
Aircraft electrification requires reliable, power-dense, high-efficient, and bidirectional rectifiers to improve the overall performance of existing aircrafts. Thus, traditional bulky passive rectifiers must be substituted by active rectifiers, satisfying the requirements imposed by up-to-date standards. However, several challenges are found in terms of [...] Read more.
Aircraft electrification requires reliable, power-dense, high-efficient, and bidirectional rectifiers to improve the overall performance of existing aircrafts. Thus, traditional bulky passive rectifiers must be substituted by active rectifiers, satisfying the requirements imposed by up-to-date standards. However, several challenges are found in terms of power controllability, due to the standardized passive rectifier-based operating conditions. This work presents the implementation of an active rectifier modular architecture for aircraft applications. An analysis of the technical difficulties and limitations was performed and three innovative modular architectures are proposed and designed. In order to find the most suitable architecture, a comparison framework is proposed, focusing on efficiency, volume, and reliability parameters. From the comparative analysis, it can be concluded that the two-stage configuration architecture is a good solution in terms of semiconductor life expectancy and low volume. However, if converter redundancies are required, the single-stage with STATCOM configuration is an excellent trade-off between low volume, redundancy, and cost-effectiveness. Full article
(This article belongs to the Special Issue Electric Aircraft: Storage Systems, Power Electronics, and Control)
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17 pages, 2124 KiB  
Article
Optimal Guidance Laws for a Hypersonic Multiplayer Pursuit-Evasion Game Based on a Differential Game Strategy
by Haizhao Liang, Zhi Li, Jinze Wu, Yu Zheng, Hongyu Chu and Jianying Wang
Aerospace 2022, 9(2), 97; https://doi.org/10.3390/aerospace9020097 - 12 Feb 2022
Cited by 13 | Viewed by 3246
Abstract
The guidance problem of a confrontation between an interceptor, a hypersonic vehicle, and an active defender is investigated in this paper. As a hypersonic multiplayer pursuit-evasion game, the optimal guidance scheme for each adversary in the engagement is proposed on the basis of [...] Read more.
The guidance problem of a confrontation between an interceptor, a hypersonic vehicle, and an active defender is investigated in this paper. As a hypersonic multiplayer pursuit-evasion game, the optimal guidance scheme for each adversary in the engagement is proposed on the basis of linear-quadratic differential game strategy. In this setting, the angle of attack is designed as the output of guidance laws, in order to match up with the nonlinear dynamics of adversaries. Analytical expressions of the guidance laws are obtained by solving the Riccati differential equation derived by the closed-loop system. Furthermore, the satisfaction of the saddle-point condition of the proposed guidance laws is proven mathematically according to the minimax principle. Finally, nonlinear numerical examples based on 3-DOF dynamics of hypersonic vehicles are presented, to validate the analytical analysis in this study. By comparing different guidance schemes, the effectiveness of the proposed guidance strategies is demonstrated. Players in the engagement could improve their performance in confrontation by employing the proposed optimal guidance approaches with appropriate weight parameters. Full article
(This article belongs to the Special Issue Hypersonics: Emerging Research)
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28 pages, 2014 KiB  
Article
Neural Network Prediction for Ice Shapes on Airfoils Using iceFoam Simulations
by Sergei Strijhak, Daniil Ryazanov, Konstantin Koshelev and Aleksandr Ivanov
Aerospace 2022, 9(2), 96; https://doi.org/10.3390/aerospace9020096 - 12 Feb 2022
Cited by 18 | Viewed by 4001
Abstract
In this article the procedure and method for the ice accretion prediction for different airfoils using artificial neural networks (ANNs) are discussed. A dataset for the neural network is based on the numerical experiment results—obtained through iceFoam solver—with four airfoils (NACA0012, General Aviation, [...] Read more.
In this article the procedure and method for the ice accretion prediction for different airfoils using artificial neural networks (ANNs) are discussed. A dataset for the neural network is based on the numerical experiment results—obtained through iceFoam solver—with four airfoils (NACA0012, General Aviation, Business Jet, and Commercial Transport). Input data for neural networks include airfoil and ice geometries, transformed into a set of parameters using a parabolic coordinate system and Fourier series expansion. Besides input features include physical parameters of flow (velocity, temperature, droplets diameter, liquid water content, time of ice accretion) and angle of attack. The novelty of this work is in that the neural network dataset includes various airfoils and the data augmentation technique being a combination of all time slices. Several artificial neural networks (ANNs), fully connected networks (FCNNs), and convolutional networks (CNNs) were trained to predict airfoil ice shapes. Two different loss functions were considered. In order to improve performance of models, batch normalization and dropout layers were used. The most accurate results of ice shape prediction were obtained using CNN and FCNN that applied batch normalization and dropout layers to output neurons of each layer. Full article
(This article belongs to the Special Issue Deicing and Anti-Icing of Aircraft (Volume II))
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18 pages, 1404 KiB  
Article
Design of a Low-Cost Air Bearing Testbed for Nano CMG Maneuvers
by Charalampos Papakonstantinou, Georgios Moraitis, Vaios Lappas and Vassilis Kostopoulos
Aerospace 2022, 9(2), 95; https://doi.org/10.3390/aerospace9020095 - 12 Feb 2022
Cited by 8 | Viewed by 4352
Abstract
In this paper, a low-cost, miniature spacecraft attitude control simulator is presented for testing miniature actuators such as Nano Control Moment Gyroscopes (CMGs) for simple maneuvers. The experimental setup is composed by an attitude control system (ACS) that mainly consists of a four-CMG [...] Read more.
In this paper, a low-cost, miniature spacecraft attitude control simulator is presented for testing miniature actuators such as Nano Control Moment Gyroscopes (CMGs) for simple maneuvers. The experimental setup is composed by an attitude control system (ACS) that mainly consists of a four-CMG cluster in a pyramid configuration and a custom-made air bearing. The one-degree-of-freedom (DoF) air bearing is fabricated to reproduce the frictionless conditions of a nano-satellite in orbit. The ACS is made exclusively using low-cost commercial-off-the-shelf (COTS) components, whilst the air bearing is made using 3D-printed parts. Both hardware and software implementations are described in detail and the performance of the developed simulator is evaluated by two maneuver experiments. Despite the manufacturing imperfections, the ACS is capable of providing higher angular velocities than previously presented in the literature while following the theoretical or simulation data. The results indicate that it is possible to manufacture a low-cost, miniature actuator such as a CMG, using COTS components to demonstrate the operation of an agile nano-satellite. Any deviations from the theoretical values are addressed and several improvements are discussed to further enhance the performance of the air bearing testing platform. Full article
(This article belongs to the Special Issue Recent Advances in Spacecraft Dynamics and Control)
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19 pages, 7191 KiB  
Article
Design of a Multi-Constraint Formation Controller Based on Improved MPC and Consensus for Quadrotors
by Danghui Yan, Weiguo Zhang and Hang Chen
Aerospace 2022, 9(2), 94; https://doi.org/10.3390/aerospace9020094 - 11 Feb 2022
Cited by 14 | Viewed by 3018
Abstract
The formation flight of quadrotor unmanned aerial vehicles (UAVs) is a complex multi-constraint process. When designing a formation controller, the dynamic model of the UAV itself has modeling errors and uncertainties. Model predictive control (MPC) is one of the best control methods for [...] Read more.
The formation flight of quadrotor unmanned aerial vehicles (UAVs) is a complex multi-constraint process. When designing a formation controller, the dynamic model of the UAV itself has modeling errors and uncertainties. Model predictive control (MPC) is one of the best control methods for solving the constrained problem. First, a mathematical model of the quadrotor considering disturbance and uncertainty is established using the Lagrange–Euler formulation and is divided into a rotational subsystem (RS) and a translational subsystem (TS). Here, an improved MPC (IMPC) strategy based on an error model is introduced for the control of UAVs. The tracking errors caused by synthesis disturbance can be eliminated because of the integrator embedded in the augmented model. In addition, by modifying the parameters of the cost function, not only can the degree of stability of the closed-loop subsystem be specified, but also numerical problems in the MPC calculation can be improved. The simulation results demonstrate the stability of the designed controller in formation maintenance and its robustness to external disturbances and uncertainties. Full article
(This article belongs to the Special Issue Flight Simulation and Aircraft Autonomy)
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25 pages, 1285 KiB  
Article
RNN-CNN Hybrid Model to Predict C-ATC CAPACITY Regulations for En-Route Traffic
by Sergi Mas-Pujol, Esther Salamí and Enric Pastor
Aerospace 2022, 9(2), 93; https://doi.org/10.3390/aerospace9020093 - 10 Feb 2022
Cited by 8 | Viewed by 3164
Abstract
Meeting the demand with the available airspace capacity is one of the most challenging problems faced by Air Traffic Management. Nowadays, this collaborative Demand–Capacity Balancing process often ends up enforcing Air Traffic Flow Management regulations when capacity cannot be adjusted. This process to [...] Read more.
Meeting the demand with the available airspace capacity is one of the most challenging problems faced by Air Traffic Management. Nowadays, this collaborative Demand–Capacity Balancing process often ends up enforcing Air Traffic Flow Management regulations when capacity cannot be adjusted. This process to decide if a regulation is needed is time consuming and relies heavily on human knowledge. This article studies three different Air Traffic Management frameworks aiming to improve the cost-efficiency for Flow Manager Positions and Network Manager operators when facing the detection of regulations. For this purpose, two already tested Deep Learning models are combined, creating different hybrid models. A Recurrent Neural Network is used to process scalar variables to extract the overall airspace characteristics, and a Convolutional Neural Network is used to process artificial images exhibiting the specific airspace configuration. The models are validated using historical data from two of the most regulated European regions, resulting in a novel framework that could be used across Air Traffic Control centers. For the best hybrid model, using a cascade architecture, an average accuracy of 88.45% is obtained, with an average recall of 92.16%, and an average precision of 86.85%, across different traffic volumes. Moreover, two different techniques for model explainability are used to provide a theoretical understanding of its behavior and understand the reasons behind the predictions. Full article
(This article belongs to the Section Air Traffic and Transportation)
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20 pages, 7031 KiB  
Article
Characterization of Residual Stresses and Grain Structure in Hot Forging of GH4169
by Zibiao Wang, Guangsha Hou, Yang Zhao, Jianfei Sun, Jiangzhen Guo and Wuyi Chen
Aerospace 2022, 9(2), 92; https://doi.org/10.3390/aerospace9020092 - 10 Feb 2022
Cited by 5 | Viewed by 3229
Abstract
Residual stresses (RS) in hot forging severely degrade the machining accuracy and stability of super alloy parts. This is the main reason for deformation during subsequent mechanical machining. RS need recognition, as well as the microstructure and properties achieved by forging. In this [...] Read more.
Residual stresses (RS) in hot forging severely degrade the machining accuracy and stability of super alloy parts. This is the main reason for deformation during subsequent mechanical machining. RS need recognition, as well as the microstructure and properties achieved by forging. In this study, a simulation and experimental research on the single-pass compression of GH4169 are presented. RS variations with forging temperature, loading speed, and cooling speed are established by finite element (FE) simulation. Based on the FE results, an experiment is conducted at a temperature of 1020 ℃, loading speed of 25 mm/s, and press amount of 16 mm, immediately followed by water cooling. A new layer-stripping method is put forward for the high-efficiency measurement and correction of interior RS. Compared with the traditional strain gauge layer-stripping method, the measurement efficiency of the new layer-stripping method is increased by 10 times. Meanwhile, grain photographs are collected and grain size evolution is summarized; thus, the RS is characterized and evaluated from the angle of grains. It is demonstrated that the RS level rises with the increase in forging temperature, loading speed, and cooling speed, while the cooling method influences both the stress value and distribution. Compressive RS changes to tensile, while the average grain size reduces from the surfaces to the center. In the compressive regions, stress values share the same rules as grain size, while, in the tensile regions, they are contrary. The RS levels are divided according to the grain degree standard. According to the residual stress and grain distribution law of the blank, the optimal position of the part in the blank can be determined. Compared with the center position of the part in the blank, the residual stress of the part is reduced by 70%. The results provide useful strategies for the better design of forging technology, qualification examinations, and subsequent mechanical machining. Full article
(This article belongs to the Special Issue Laser Manufacturing Technologies for Aerospace Applications)
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19 pages, 1228 KiB  
Review
Aircraft 4D Trajectory Prediction in Civil Aviation: A Review
by Weili Zeng, Xiao Chu, Zhengfeng Xu, Yan Liu and Zhibin Quan
Aerospace 2022, 9(2), 91; https://doi.org/10.3390/aerospace9020091 - 10 Feb 2022
Cited by 42 | Viewed by 16106
Abstract
Aircraft four dimensional (4D, including longitude, latitude, altitude and time) trajectory prediction is a key technology for existing automation systems and the basis for future trajectory-based operations. This paper firstly summarizes the background and significance of the trajectory prediction problems and then introduces [...] Read more.
Aircraft four dimensional (4D, including longitude, latitude, altitude and time) trajectory prediction is a key technology for existing automation systems and the basis for future trajectory-based operations. This paper firstly summarizes the background and significance of the trajectory prediction problems and then introduces the definition and basic process of trajectory prediction, including four modules: preparation, prediction, update, and output. In addition, the trajectory prediction methods are summarized into three types: the state estimation model, the Kinetic model, and the machine learning model, and in-depth analysis of various models is carried out. Further, the relevant databases required for the study are introduced, including the aircraft performance database, aircraft monitoring database, and meteorological database. Finally, challenges and future development directions of the current trajectory prediction problem are summarized. Full article
(This article belongs to the Special Issue Closing the Gap in Aircraft Trajectories: Enhancing Optimization and Prediction Approaches)
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19 pages, 6664 KiB  
Article
Flocking Bird Strikes on Engine Fan Blades and Their Effect on Rotor System: A Numerical Simulation
by Bin Wu, Jiewei Lin, Anshun Xie, Ning Wang, Guichang Zhang, Junhong Zhang and Huwei Dai
Aerospace 2022, 9(2), 90; https://doi.org/10.3390/aerospace9020090 - 10 Feb 2022
Cited by 4 | Viewed by 3406
Abstract
Bird strikes are a common, serious, and devastating event in aviation accidents, and multi-bird strikes are also frequently reported. A numerical multi-bird-strike simulation was performed to investigate the effect of flocking birds striking on engine blades. The smooth particle hydrodynamics (SPH) method was [...] Read more.
Bird strikes are a common, serious, and devastating event in aviation accidents, and multi-bird strikes are also frequently reported. A numerical multi-bird-strike simulation was performed to investigate the effect of flocking birds striking on engine blades. The smooth particle hydrodynamics (SPH) method was adopted in the hemispherical-ended bird substitute model, and the finite element method (FEM) with EOS state equation was adopted for the fan model as well. Impact analyses have been presented using different flocking birds and impact location distributions. A “0-2-1” supported rotor system dynamic model was established to study the effect of the multi-bird-strike impact forces on the rotor system. The results show that bird-strike severity is related to the impact location distribution, with blade-root impacts being the most dangerous. The small flocking bird strikes had little effect on the fan compared to the cases of medium flocking birds and the large single bird. The dynamic response of the fan to the small flocking birds was the same as without a bird strike, while the other cases changed the motion period and excited the rotor first-order vibration. Full article
(This article belongs to the Section Aeronautics)
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22 pages, 3913 KiB  
Article
Low Speed Aerodynamic Analysis of the N2A Hybrid Wing–Body
by Andrea Aprovitola, Francesco Aurisicchio, Pasquale Emanuele Di Nuzzo, Giuseppe Pezzella and Antonio Viviani
Aerospace 2022, 9(2), 89; https://doi.org/10.3390/aerospace9020089 - 10 Feb 2022
Cited by 2 | Viewed by 6029
Abstract
Reduction of atmospheric emissions is currently a mandatory requirement for aircraft manufacturers. Several studies performed on Blended Wing–Body configurations showed a promising capability of reducing fuel consumption by increasing, at the same time, passengers’ transport capabilities. Although several aerodynamic studies are available at [...] Read more.
Reduction of atmospheric emissions is currently a mandatory requirement for aircraft manufacturers. Several studies performed on Blended Wing–Body configurations showed a promising capability of reducing fuel consumption by increasing, at the same time, passengers’ transport capabilities. Although several aerodynamic studies are available at transonic speeds, low-speed evaluations of aerodynamic performances of Blended Wing Body aircrafts are less investigated. In this framework, the present paper deals with the aerodynamic performance of the N2A aircraft prototype at low-Mach number conditions. Aircraft longitudinal aerodynamics is addressed at M∞=0.2 with steady state three-dimensional RANS simulations carried out at two Reynolds numbers equal to 6.60×106 and 1.27×108, respectively. The former refers to an experimental test campaign performed at NASA Langley 14-by-22 foot subsonic tunnel, while the latter is related to free-flight conditions close to an approach and landing phase. Flowfield simulations are performed using the Computational Fluid Dynamic code FLUENT and the SU2 open-source code, currently adopted for research applications. Numerical solutions are validated by using available experimental data with reference to lift, drag, pitching moment and drag polar estimations. Pre-stall and post-stall aerodynamic behaviour through mean flow-field visualization along with the comparison of pressure distributions at several AoAs is addressed. Furthermore, the effect of convective discretization on a numerical solution for SU2 is discussed. Results indicate a good agreement with available experimental predictions. The present study aims to bridge existing computations at a Eulerian low-Mach number, with RANS computations and constitutes a further test-case for SU2 code with respect to a full aircraft configuration. Full article
(This article belongs to the Special Issue Advances in Aerospace Sciences and Technology II)
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19 pages, 1771 KiB  
Article
Multiple Delay-Dependent Guaranteed Cost Control for Distributed Engine Control Systems with Aging and Deterioration
by Yifeng Chen, Yingqing Guo, Xinghui Yan and Haotian Mao
Aerospace 2022, 9(2), 88; https://doi.org/10.3390/aerospace9020088 - 9 Feb 2022
Cited by 1 | Viewed by 2058
Abstract
Distributed control architecture can bring many benefits to the engine control system, but the delay and packet dropout introduced by network communication will bring negative effects to the control system. The aging and deterioration of the engine are also obstacles in the design [...] Read more.
Distributed control architecture can bring many benefits to the engine control system, but the delay and packet dropout introduced by network communication will bring negative effects to the control system. The aging and deterioration of the engine are also obstacles in the design of the engine control system. This paper is concerned with the problem of guaranteed cost control for a distributed engine control system (DECS) with these negative constraints. Firstly, a model of DECS with multiple delays, packet dropouts and uncertainties is built. Secondly, a multiple delay-dependent guaranteed cost controller design method is proposed in the form of a set of linear matrix inequalities (LMIs). The non-convex optimal controller design problem is transformed into a convex optimization problem through the cone complementarity linearization (CCL) method, and the suboptimal controller is designed iteratively. Thirdly, turboshaft engine aging and deterioration are treated as sources of uncertainties, and the norm-bounded uncertain model of the turboshaft engine is modeled. Finally, the numerical simulations demonstrate the effectiveness and applicability of the guaranteed cost controller designed for DECS with multiple delays, packet dropouts, engine aging and deteriorations. Full article
(This article belongs to the Section Aeronautics)
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27 pages, 68406 KiB  
Article
Numerical Investigation and Parameter Sensitivity Analysis on Flow and Heat Transfer Performance of Jet Array Impingement Cooling in a Quasi-Leading-Edge Channel
by Lei Xi, Jianmin Gao, Liang Xu, Zhen Zhao, Qicheng Ruan and Yunlong Li
Aerospace 2022, 9(2), 87; https://doi.org/10.3390/aerospace9020087 - 9 Feb 2022
Cited by 8 | Viewed by 2279
Abstract
In this study, numerical simulations were carried out to investigate the flow and heat transfer characteristics of jet array impingement cooling in the quasi-leading-edge channel of gas turbine blades. The influence laws of Reynolds number (Re, 10,000 to 50,000), hole diameter-to-impingement [...] Read more.
In this study, numerical simulations were carried out to investigate the flow and heat transfer characteristics of jet array impingement cooling in the quasi-leading-edge channel of gas turbine blades. The influence laws of Reynolds number (Re, 10,000 to 50,000), hole diameter-to-impingement spacing ratio (d/H, 0.5 to 0.9), hole spacing-to-impingement spacing ratio (S/H, 2 to 6), and Prandtl number (Pr, 0.690 to 0.968) on flow performance, heat transfer performance, and comprehensive thermal performance were examined, and the corresponding empirical correlations were fitted. The results show that increasing the d/H and reducing the S/H can effectively reduce the pressure loss coefficient in the quasi-leading-edge channel. Increasing the Re, reducing the d/H, and increasing the S/H can effectively enhance the heat transfer effect of the target wall. When d/H = 0.6 at lower Reynolds numbers and S/H = 5 at higher Reynolds numbers, the comprehensive thermodynamic coefficient reaches its maximum values. The average Nusselt numbers and comprehensive thermal coefficients of the quasi-leading-edge channel for steam cooling are both higher than those for air cooling. The pressure loss coefficient of the quasi-leading-edge channel is most sensitive to the change in d/H but is not sensitive to the change in Re. The average Nusselt number of the quasi-leading-edge channel is most sensitive to the change in Re and is least sensitive to the change in Pr. The comprehensive thermal coefficient of the quasi-leading-edge channel is most sensitive to the change in Re. The findings may provide a reference for the design of a steam-cooling structure in the leading edge channel of high-temperature turbine blades. Full article
(This article belongs to the Special Issue Cooling/Heat transfer (Volume II))
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19 pages, 6428 KiB  
Article
Global Optimization of UAV Area Coverage Path Planning Based on Good Point Set and Genetic Algorithm
by Jinbiao Yuan, Zhenbao Liu, Yeda Lian, Lulu Chen, Qiang An, Lina Wang and Bodi Ma
Aerospace 2022, 9(2), 86; https://doi.org/10.3390/aerospace9020086 - 7 Feb 2022
Cited by 37 | Viewed by 3888
Abstract
When performing area coverage tasks in some special scenarios, fixed-wing aircraft conventionally adopt the scan-type of path planning, where the distance between two adjacent tracks is usually less than the minimum turning radius of the aircraft. This results in increased energy consumption during [...] Read more.
When performing area coverage tasks in some special scenarios, fixed-wing aircraft conventionally adopt the scan-type of path planning, where the distance between two adjacent tracks is usually less than the minimum turning radius of the aircraft. This results in increased energy consumption during turning between adjacent tracks, which means a reduced task execution efficiency. To address this problem, the current paper proposes an area coverage path planning method for a fixed-wing unmanned aerial vehicle (UAV) based on an improved genetic algorithm. The algorithm improves the primary population generation of the traditional genetic algorithm, with the help of better crossover operator and mutation operator for the genetic operation. More specifically, the good point set algorithm (GPSA) is first used to generate a primary population that has a more uniform distribution than that of the random algorithm. Then, the heuristic crossover operator and the random interval inverse mutation operator are employed to reduce the risk of local optimization. The proposed algorithm is verified in tasks with different numbers of paths. A comparison with the conventional genetic algorithm (GA) shows that our algorithm can converge to a better solution. Full article
(This article belongs to the Topic GNSS Measurement Technique in Aerial Navigation)
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