Review Reports

Round 1

Reviewer 1 Report

Relate literature review / state of the art to the paper --> what is its significance?

Is turbulence model relevant - how sensitive are results to its assumption.

Textual reference to Figure 3 is incorrect, actually Figure 4.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Summary: the well-structured paper studied numerically and experimentally the external flow characteristics and the pressure fluctuation of a submersible tubular pumping system. The numerically calculated performance curve agrees with the experimental data and the unsteady CFD was confirmed by the results of high-frequency pressure measurement. The main conclusion is that the passing frequency is an important parameter. Is that not well established in the literature? In how far is this a novelty and what other conclusions can be drawn from the extensively described numerical and experimental setup?

abstract:

The abstract should be more compact and highlight more the main findings. Author can elaborate on the implications (usefulness) of the findings. The abstract can be limited to the introduction of tubular pumping systems, defining the main issue, describing the numerical and experiment approach then moving to results and implications. The abstract in its actual form switches from methodology to results then back to methodology.

Introduction:

the subject of the analysis is well introduced. Problematic of vibration and hydraulic noise identified: preventing the stable operation of the pump. the author reported on related work. Mentioning that the research on tubular pumps is rare. results are a start step toward reaching the stable operation of those pumps. How can they be further used toward this purpose?

Numerical setup:

line 112: the author performed a grid study. The author could provide the results of the grid study as the evolution of some key measures with the increase of the mesh resolution (It is important to give the mesh size in number of cells and the execution time). how do you get the different operating conditions?

Experimental system:

line 131: a small .. test bench: is the experiment done on a different pump size than the CFD?

Results:

The analysis of the pressure fluctuation on the frequency domain is interesting but can be made clearer for non-experts. Moreover, the author can elaborate more on the disagreement between measurements and FFT in some positions. figure 6: points on Q=24 are not on the curve. Why? line 177: why the CFD is over predictive in one part and under predictive in the other? what is z in equ 4 what is the full fold frequency does it coincide with the peak at Nf=3. line 218: elaborate on the effect of the FFT form on the results. May show the results of different FFT forms to check the effect. line 223: what is a shift frequency. Line 226: the model test is caused by the influence of bubbles: can you elaborate, please line 259: please elaborate on the implication of the presented results and possible future work.

Conclusion:

please add that the first point is about steady-state CFD simulation

 

 

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript submitted for review presents the problem of the study of external flow characteristics and pressure flucturation of a submersible tubular pumping system using a combination of experiment and numerical simulation. Authors performed numerical simulation using commercial CFD software ANSYS CFX-14.5.

In the introduction in Chapter 1, the authors present a review of the literature indicating how important is problem of the pressure pulsation and the unsteady flow inside the pumps of this type. Unfortunately, the reviewer was not able to trace the articles indicated in the bibliography. Items 1 to 4 are articles in Chinese. In addition, the authors incorrectly provided journal: Journal of Agricultural Machinery. In fact, these articles are in a non-English language in Transactions of the Chinese Society for Agricultural Machinery. The same remark applies to headings 25 and 26 -  however here, the authors correctly define the journal.

In the remainder of this chapter, the authors present a literature review for the use of numerical simulations using CFD to study internal pressure pulsation of pumps. The reviewer has no fundamental comments on the articles cited here, except for item 28, which is not available and it is not known whether this is an article or a dissertation or a report on the work?

I believe that the authors should thoroughly improve the literature review, indicating the items published in English.

Chapter 2.

The reviewer has no comments except for two editorial comments: no subsection number (line 100) - 2.3 ??? and on line 118, after the colon should be lowercase.

Chapter 3.

For the purposes of this work, a model of the tested pump system was prepared. Basic dimensions are missing (e.g. in Figure 4). The authors also cite formulas (1-3) in this chapter - simple and obvious, but require a reference to the literature.

In chapter 4 the authors present the results of the simulations carried out. Figure 6 shows the results of numerical simulations combined with the results of measurements. It is not explained what are points and what are solid lines. Is this an approximation effect? The authors summarized the results obtained as consistent. At least a correlation or some other statistical measure should be specified. the same applies to the results in Figure 8. Please also describe the details of used the Fast Fourier Transform analysis. On page 8 there are also some editorial errors - e.g. on lines 214, 233.

In chapter 6? 5? Conclusions (the authors missed 5) valid conclusions resulting from the research presented in the manuscript were quoted. However, it seems that the authors are trying to extend the results obtained on a small model of the tested pumping system to the operation of similar systems on a real scale. Is it entitled? The conclusions lack references from model research to the work of real objects.

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

I accept all responses and changes made by the authors in the manuscript. However, please check whether such extensive changes have not affected the quality of the article from the editor's side

Author Response

First of all, the authors wish to thank the Reviewer’s comments.

In the first round of review comments, the reviewers mentioned that my literature review should be combined with the content of the paper to clarify the importance of the research, so I rearranged the literature review and combined the review with the content of the paper. Some changes made the review more logical and highlighted the importance of the research. There were not many changes to the references, only the order was changed. The extensive changes do not affected the quality of the article, and do not change the main context of this paper.