Lubricants

Research

14 pages, 2509 KiB

Open AccessArticle

Analyzing the Efficacy of Nickel Plating Coating in Hydraulic Pipeline Drag Reduction

by Xue Wang, Junjie Zhou, Bowen Yao and Wenbo Liao

Lubricants 2024, 12(2), 37; https://doi.org/10.3390/lubricants12020037 - 26 Jan 2024

Cited by 2 | Viewed by 1577

This study delves into the drag-reducing properties of nickel plating coatings applied to hydraulic pipelines. To investigate the drag reduction characteristics of pipeline coatings, we designed a specialized experimental apparatus to conduct deceleration experiments. The primary objective was to systematically assess the drag [...] Read more.

This study delves into the drag-reducing properties of nickel plating coatings applied to hydraulic pipelines. To investigate the drag reduction characteristics of pipeline coatings, we designed a specialized experimental apparatus to conduct deceleration experiments. The primary objective was to systematically assess the drag reduction effect of varying coating thicknesses on liquid flow within the pipeline. Chemical nickel plating was employed for preparing drag reduction coatings with diverse thicknesses, achieved through precise adjustments in the composition and operating conditions of the plating solution. In the design of the experimental apparatus, careful consideration was given to crucial parameters such as the inner diameter of the pipeline, the inlet flow rate, and the control of experimental variables. It quantitatively assesses how varying coating thicknesses, flow velocities, and pipeline diameters impact the pipelines’ resistance to flow. By meticulously measuring the pressure differential across the pipeline, the research evaluates the extent of drag reduction afforded by the coatings and simultaneously elucidates the underlying mechanisms. Findings indicate a peak drag reduction rate of 5% under conditions of a 20 µm-thick nickel coating, 5 m/s flow velocity, and a 10 mm pipeline diameter. This study aims to comprehend how coatings affect linear losses along the pipeline, thereby establishing the groundwork for optimizing drag reduction technology. These outcomes highlight the coatings’ potential to mitigate linear losses due to shear stress during fluid transport, offering a viable solution to enhance hydraulic pipeline efficiency with significant industrial implications. Full article

(This article belongs to the Special Issue Dynamics of Lubricated Interfaces)

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13 pages, 4685 KiB

Open AccessArticle

The Effect of Slider Configuration on Lubricant Depletion at the Slider/Disk Contact Interface

by Yuxin Chen, Dongdong Zhou and Zhengqiang Tang

Lubricants 2024, 12(1), 17; https://doi.org/10.3390/lubricants12010017 - 8 Jan 2024

Viewed by 1837

Abstract

With decreasing clearance between the protrusion of a slider and a disk interface, there is a higher likelihood of contact occurring during shock or vibration experienced by hard disk drives (HDDs), which may induce lubricant depletion. Based on the molecular dynamics (MD) model [...] Read more.

With decreasing clearance between the protrusion of a slider and a disk interface, there is a higher likelihood of contact occurring during shock or vibration experienced by hard disk drives (HDDs), which may induce lubricant depletion. Based on the molecular dynamics (MD) model of perfluoropolyether lubricant with a coarse-grained beads spring approach, we compared the slider configurations’ influence on the lubricant transfer volume quantitatively. By further investigating the parameters of the cylindrical asperities, including the width and depth, as well as considering the asperity amounts of the slider, we successfully observed the lubricant depletion process during slider and disk contact. The results demonstrate that the penetration depth was reduced as the asperity amount increased, mainly owing to the increased contact area between the surfaces. The decreasing depth of the asperity and the increasing width of the asperity helped to reduce the depletion volume. In addition, the utilization of a cylindrical slider configuration can contribute to a reduction in lubricant depletion resulting from contact between the head and disk. Full article

(This article belongs to the Special Issue Dynamics of Lubricated Interfaces)

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21 pages, 11086 KiB

Open AccessArticle

Influence of Nitrile Butadiene Rubber (NBR) Shore Hardness and Polytetrafluoroethylene (PTFE) Elastic Modulus on the Sealing Characteristics of Step Rod Seals

by Bingqing Wang, Xiaoxuan Li, Xudong Peng, Yuntang Li, Xiang Li, Yuan Chen and Jie Jin

Lubricants 2023, 11(9), 367; https://doi.org/10.3390/lubricants11090367 - 31 Aug 2023

Viewed by 2267

Abstract

The influence of NBR Shore hardness and PTFE elastic modulus on the sealing characteristics of step rod seals is analyzed in this paper based on the developed mixed elastohydrodynamic lubrication (EHL) model. The optimized selection studies of NBR Shore hardness and PTFE elastic [...] Read more.

The influence of NBR Shore hardness and PTFE elastic modulus on the sealing characteristics of step rod seals is analyzed in this paper based on the developed mixed elastohydrodynamic lubrication (EHL) model. The optimized selection studies of NBR Shore hardness and PTFE elastic modulus under different operating conditions are carried out based on the principle of minimizing net leakage and friction power loss. Results show that the Shore hardness of the NBR O-ring and, in particular, the elastic modulus of the PTFE ring has a significant effect on the sealing characteristics. Although the high values of these parameters result in high friction forces, they are beneficial for leakage control. To achieve both low leakage and low friction, it is recommended that high hardness and low modulus are selected for moderate-low pressure or high speed conditions, but low hardness and high modulus are selected for high pressure or low speed conditions. Full article

(This article belongs to the Special Issue Dynamics of Lubricated Interfaces)

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20 pages, 8933 KiB

Open AccessArticle

Research on Nonconstant and Discontinuous Pumping Characteristics of the Concrete Pump Truck

by Yafeng Ren, Chunyang Bi, Wenwen Lu, Jinning Zhi, Weifeng Yang, Jie Li and Haiwei Wang

Lubricants 2023, 11(5), 217; https://doi.org/10.3390/lubricants11050217 - 13 May 2023

Viewed by 1677

Abstract

The nonconstant concrete flow due to the alternating pumping of the twin cylinder of the hydraulic pump will cause vibration of concrete pump trucks. Furthermore, the discontinuous pumping of concrete caused by inadequate suction and air doping will exacerbate the vibration. In order [...] Read more.

The nonconstant concrete flow due to the alternating pumping of the twin cylinder of the hydraulic pump will cause vibration of concrete pump trucks. Furthermore, the discontinuous pumping of concrete caused by inadequate suction and air doping will exacerbate the vibration. In order to study the effect of nonconstant and discontinuous pumping of concrete on the dynamic response and vibrational stability of the whole vehicle, multi-fluid pumping models with concrete-lubrication gas for straight and elbow pipes are established, respectively, and the boundary conditions of periodic pumping speed are taken into account to compare the rheological characteristics of concrete and the exciting force on the pipe wall under nonconstant pumping, discontinuous pumping and nonconstant discontinuous pumping conditions. Results show that the pipe pressure and the exciting force vary periodically with the pumping speed under nonconstant pumping conditions, and the peak-to-peak value of the pipe pressure and excitation for discontinuous pumping depend on the volume fraction and distribution state of the gas in the pipe. Full article

(This article belongs to the Special Issue Dynamics of Lubricated Interfaces)

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22 pages, 15416 KiB

Open AccessArticle

Study on the Nano-Friction Behavior of Nickel-Based Ag Film Composites Based on Molecular Dynamics

by Wenbang Chen, Weihua Chen, Zongxiao Zhu, Min Zheng, Xingchun Wei, Tianzuo Shi and Dingfeng Qu

Lubricants 2023, 11(3), 110; https://doi.org/10.3390/lubricants11030110 - 28 Feb 2023

Cited by 1 | Viewed by 1671

Abstract

The nano-friction behavior of nickel-based Ag film composites was evaluated using molecular dynamics simulations. The mechanical properties, the surface morphology, the migration behavior of Ag atoms and the defect evolution during repeated friction were investigated. Our results show that the poor mechanical properties [...] Read more.

The nano-friction behavior of nickel-based Ag film composites was evaluated using molecular dynamics simulations. The mechanical properties, the surface morphology, the migration behavior of Ag atoms and the defect evolution during repeated friction were investigated. Our results show that the poor mechanical properties of the Ag film surface at the first stage of friction are related to a large amount of abrasive chip pileup. The slip channel with low shear strength formed by secondary friction significantly reduces the friction coefficient of the Ag film surface. Meanwhile, the migration of Ag atoms at the two-phase interface relies mainly on the repeated friction of the grinding ball, and the friction coefficient of the nickel surface decreases as the number of migrating atoms increases. In addition, the extension of defects inside the Ag film and atomic displacement is hindered by the two-phase interface. The defects inside the Ag film near the friction zone gradually evolve from an intrinsic stacking fault to a horizontal stacking fault as the friction proceeds. This is attributed to the horizontal layer-by-layer motion of Ag atoms, promoting the formation of horizontal stacking faults. Full article

(This article belongs to the Special Issue Dynamics of Lubricated Interfaces)

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22 pages, 6062 KiB

Open AccessArticle

Study on Sealing Characteristics of Compliant Foil Face Gas Seal under Typical Hypervelocity Gas Effects

by Yuan Chen, Qinggang Wang, Yuntang Li, Xiaolu Li, Bingqing Wang and Jie Jin

Lubricants 2023, 11(2), 46; https://doi.org/10.3390/lubricants11020046 - 28 Jan 2023

Cited by 5 | Viewed by 1736

Abstract

In order to investigate the influence of typical hypervelocity gas effects on the gas lubrication performance of compliant foil face gas seal (CFFGS) end surfaces, the gas–elastic coupling lubrication theory model of CFFGS is modified by considering the choked flow and inertia effect, [...] Read more.

In order to investigate the influence of typical hypervelocity gas effects on the gas lubrication performance of compliant foil face gas seal (CFFGS) end surfaces, the gas–elastic coupling lubrication theory model of CFFGS is modified by considering the choked flow and inertia effect, and the lubrication performance is solved using the finite difference method. Based on the choking effect, the effect of hypervelocity choked flow on the pressure field and velocity field of the seal is analyzed, and the influence of operating parameters on the choked flow and the mechanism of choked flow on the change in dynamic lubrication and sealing performance are explored. Furthermore, based on the inertia effect, the effect of gas inertia force on the flow field, and the correlation law between the pressure field and velocity field under the influence of operating parameters are studied. Then, the relationship between the inertia effect and sealing performance are analyzed. The results show that choked flow increases sealing outlet pressure significantly, from 0.1 MPa to a maximum of 14.25 MPa, and the sealing outlet flow velocity decreases by up to 50 times. The increase in medium pressure and balance film thickness aggravate the choking effect, resulting in a 20% maximum increase in opening force and a 99.6% maximum decrease in leakage rate. In addition, the inertia effect causes obvious centrifugal movement of the gas flow. As result, the radial flow velocity reduces by up to 50%, and the pressure distribution varies widely. Especially under high rotational speed and high medium pressure, the inertia effect is enhanced to clearly reduce the opening force (max. decrement of 3.5%) and leakage rate (max. decrement of 23%). Full article

(This article belongs to the Special Issue Dynamics of Lubricated Interfaces)

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21 pages, 6678 KiB

Open AccessArticle

The Tribo-Dynamics Performance of the Lubricated Piston Skirt–Cylinder System Considering the Cylinder Liner Vibration

by Bo Zhao, Shijun Wang, Peng Xiao, Lingji Xu, Xinqing Hu, Xiancai Si and Yonghui Liu

Lubricants 2022, 10(11), 319; https://doi.org/10.3390/lubricants10110319 - 18 Nov 2022

Cited by 4 | Viewed by 2264

Abstract

The tribo-dynamics performance of the piston–cylinder system is affected by multiple physical fields. The current work presents a novel multiphysics coupling method to model and analyze the lubricated piston skirt–cylinder interface considering the cylinder liner vibration. This method is implemented by coupling multibody [...] Read more.

The tribo-dynamics performance of the piston–cylinder system is affected by multiple physical fields. The current work presents a novel multiphysics coupling method to model and analyze the lubricated piston skirt–cylinder interface considering the cylinder liner vibration. This method is implemented by coupling multibody dynamics of the crank-connecting rod–piston–cylinder system, the heat transfer of the cylinder and piston, hydrodynamics lubrication on the skirt–cylinder interface, vibration of the cylinder liner, and thermal as well as elastic deformation in the piston–cylinder system together with rheological characteristics of lubricating oil. The proposed method is adopted into a four-stroke gasoline engine to predict its dynamics and tribological characteristics, with the purpose of revealing the influence of cylinder liner vibration on the tribo-dynamics implementation of the piston–cylinder system. The results indicate that increasing the stiffness and damping coefficient of the cylinder is beneficial to suppress the vibration of the system, but it has little effect on the tribological characteristics of the piston skirt–cylinder interface. Full article

(This article belongs to the Special Issue Dynamics of Lubricated Interfaces)

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21 pages, 6738 KiB

Open AccessArticle

Dynamic Characteristics of Metal Seals in Roller Cone Bits

by Yi Ma, Yixiao Xu, Yutao Chen, Xiangkai Meng and Xudong Peng

Lubricants 2022, 10(11), 280; https://doi.org/10.3390/lubricants10110280 - 27 Oct 2022

Cited by 1 | Viewed by 1727

Abstract

During the drilling process, the sealing performance of the roller cone bits is severely challenged by the complex downhole environment and frequent vibrations. In this paper, a comprehensive thermal–fluid–solid–dynamic multi-field coupling numerical model of new-generation single energizer metal seals (SEMS2) is developed. The [...] Read more.

During the drilling process, the sealing performance of the roller cone bits is severely challenged by the complex downhole environment and frequent vibrations. In this paper, a comprehensive thermal–fluid–solid–dynamic multi-field coupling numerical model of new-generation single energizer metal seals (SEMS2) is developed. The instantaneous sealing performance of SEMS2 is studied under periodic vibration, instantaneous shock, and random vibration. Time-domain and frequency-domain changes in the sealing parameters with environmental pressures and rotational speeds under different vibrations are analyzed and compared. The results show that the liquid film distribution and lubrication state on the sealing end faces change constantly as the drill bit vibrates, which in turn affects the sealing performance of the SEMS2. The instantaneous leak rate fluctuates alternately between positive and negative under the three kinds of vibrations, aggravating the tendency of lubricant oil leakage and drilling mud invasion. With increasing environmental pressure and rotational speed, the fluctuation amplitudes of the maximum temperature increase, leakage rate, and friction torque under random vibration and instantaneous shock are significantly larger than those under periodic vibration. Our model and results have important theoretical significance for improving the design system of metal seals for drill bits. Full article

(This article belongs to the Special Issue Dynamics of Lubricated Interfaces)

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15 pages, 5396 KiB

Open AccessArticle

Effect of the Bionic Circular Groove Non-Smooth Structure on the Anti-Wear Performance of the Two-Vane Pump

by Yunqing Gu, Muhan Yan, Jiayun Yu, Ke Xia, Longbiao Ma, Jiegang Mou, Denghao Wu and Jianxing Tang

Lubricants 2022, 10(10), 231; https://doi.org/10.3390/lubricants10100231 - 22 Sep 2022

Cited by 5 | Viewed by 1688

Abstract

The characteristics of the material transported by the two-vane pump can cause the impeller to wear out, leading to a deterioration in hydraulic efficiency. Appropriately, the research goal of this paper is to consolidate the anti-wear performance of the two-vane pump conveying a [...] Read more.

The characteristics of the material transported by the two-vane pump can cause the impeller to wear out, leading to a deterioration in hydraulic efficiency. Appropriately, the research goal of this paper is to consolidate the anti-wear performance of the two-vane pump conveying a solid-liquid two-phase flow. Based on the bionic principle and the anti-wear structure of blood clams, the circular non-smooth structure adapted from blood clams is arranged in the wear-prone area. Through numerical simulation, we compare the main indexes of the pump: the head, the pressure distribution, the vortex pressures, and the average wear rate, to reveal the wear resistance mechanism of circular non-smooth structures. The results illustrate that the use of a circular non-smooth structure does not modify the external characteristics of the pump; the pressure distribution inside the impeller is similarly consistent, and the vortex pressures are all approximately the same. The average wear rate is higher when the diameter of the circular non-smooth structure is either 0.25 mm or 0.30 mm, and the simulation results are poor. At a diameter of 0.20 mm, the average wear rate of circular non-smooth blades is at its lowest point. The circular non-smooth surface structure causes impurities to be “caught” by the vortex zone and not freely struck against the wall, resulting in the particles migrating away from the blade. Full article

(This article belongs to the Special Issue Dynamics of Lubricated Interfaces)

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