Near-Wall Flow Characteristics of a Centrifugal Impeller with Low Specific Speed

Round 1

Reviewer 1 Report

The submitted manuscript deals with the analysis of near wall region flow dynamics induced by the motion of a low specific speed centrifugal propeller. To this aim, RANS and key-eps turbulence methods were included in governing equations. In my opinion it warrants publication after major revision. In the following some comments are introduced, focused in clarifying the work submitted by the author.

Abstract

Conclusions need to be better developed. Please clarify in which terms the obtained results are of interest for the readership.

Introduction.

The cited literature is comprehensive but somewhere not up-to-date; I would suggest to take also into account and discuss the following research papers:

Wang, C. et al. 2019 Pressure fluctuation–vortex interaction in an ultra-low specific-speed centrifugal pump. Journal of Low Frequency Noise Vibration and Active Control 38(2), pp. 527-543

Zhang, R., Chen, X., Guo, G., Li, R. 2018.  Reconstruction and Modal Analysis for Flow Field of Low Specific Speed Centrifugal Pump Impeller. Nongye Jixie Xuebao/Transactions of the Chinese Society for Agricultural Machinery 49(12), pp. 143-149

Liang, D. et al. 2018. The effect of front streamline wrapping angle variation in a super-low specific speed centrifugal pump. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232(23), pp. 4301-4311

Young should be replaced be Young-Do. I would say Westra and co-workers or Westra et al. instead of Westra alone. And so for the remaining ones as well.

2. Geometric model and computational grid.

A sketch where parameters such as D1, D2, b2, are indicated, would be useful-

2.1 Simulation model (Title starts with capital letter)

The sentence “The governing equations are discretized by the finite volume method based on finite element method, the convection terms are solved by the high resolution scheme, and the standard wall function is used near the fixed wall” Needs to be better explained: the author uses a FVM or a FEM scheme? What is the order of the “high” resolution scheme? Briefly explain or reference the use of the standard wall function.

2.2 experimental method and result

I see this paragraph useless. By the way, which result is the author referring to?

Figure 1 is not clear.

Figure 2. The caption needs to be more specific. It should refer to each of the subplots.

3.2 Pressure distribution near the wall region in the impeller

The unit of measure for Pascal is Pa. Amend in Figure 7 as well.

3.5 Shear stress distribution

Could you state how the obtained results are of interest for the readership?

3.6 Turbulent kinetic energy

Same as above. I see the related discussion quite poor.

Conclusions

Under three flow rates, …: which ones? (points 1 and 4)

Funding and conflict of interests are not stated.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper analyze the flow characteristics near the blade wall of centrifugal pump by means of CFD software.

The paper is well written and organized, However, there are several points that need to be addressed:

·      The Geometrical model is not well presented. The green image in figure 1 is not clear, and the geometrical characteristics must be shown in the figure (D1, D2, b2, …).

·      The boundary conditions are not precisely explained. What is the outlet flow rate? Why a outlet pressure of 1 atm was imposed? Please indicate inlet and output in the figure.

·      Figure 2 does not show the pump well.

·      There are no indications on the type of mesh used and on the use of any optimization procedures. 

·      The bibliography can be improved. Paricularly, references must be inserted in the methods section.

·      In figure 11 it is not clear to which sections the images refer. The sections should be indicated in the geometric model.

·      The grammar and spelling need careful editing.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The reviewer is satisfied with the revisions made.

Reviewer 2 Report

The paper has been improved after the review and in my opinion can be published.