Pressure Fluctuation Reduction of a Centrifugal Pump by Blade Trailing Edge Modification

Round 1

Reviewer 1 Report

The article deals with the optimization of trailing edges of a centrifugal impeller. Authors do an extensive numerical study of 4 variants of the trailing edge and evaluate the uniformity of the flow and the pressure oscillations.

Numerical simulations are conducted with standard finite volume approoach using commercial CFD package. The setup of the numerical model is clearly described and the mesh independence is confirmed by a mesh refinement study.  The results of rotor B are in good agreement with the experimental data (at least for higher flow rates).  

Conclusion:

I recommend the article for publication. I have found only few minor issues:

1. line 114, formula for specific speed: probably missing "g" in the denominator
2. line 144, the exponent -5 should be written as a superscript
3. Figs. 12 and 13 are probably plotted in polar coordinates. If so, please indicate this either in figure captions or in the text.

Final note:

It will be very interesting to see the experimental results (aka Fig. 18) for the original (prototype) rotor in order to see the decrease of fluctuations for optimized one. Although I'm aware that the experiments are usually very expensive.

 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Review of manuscript "Pressure fluctuation reduction of a centrifugal pump by blade trailing edge modification, " by Huang, Zeng, Qian, Wu, Shi, and Qian (processes-1309188).

The document presents a numerical study of effect of the blade's trailing edge geometry on the unsteady pressure fluctuations on the blade, with the aim to reduce them. The paper follows a logical structure, with appropriate research tools and presentation of results.  However, at this moment I can not advise acceptance as there are several issues that need to be changed/implemented. I list them below in 11 points: 

 

1. line 7: Only official work email should be used, I think the usage of "[email protected]" is very inappropriate.

2. There are only minor language changes required, such as punctuations or articles that are missing. As a mere example: (line 35) This sentence should start with "The".

3. I think the introduction does not introduce the topic of the paper well, as not enough context is given. For instance, The authors should mention that there are other ways of reducing the unsteady loading. In this context, Trailing edge blowing (as applied to propellers) should be mentioned. The following 7 reference should be added: 

General centrifugal pump & unsteady pressure:

[REF1] Kaupert, Staubli (1999): The unsteady pressure field in a high specific speed centrifugal pump impeller—part I: influence of the volute, Journal of Fluids Engineering, https://doi.org/10.1115/1.2823514

[REF2] Dong, Chu, Katz (1997): Effect of modification to tongue and impeller geometry on unsteady flow, pressure fluctuations, and noise in a centrifugal pump, Journal of Turbomachinery, 
https://doi.org/10.1115/1.2841152

[REF3] Gonzalez, Fernandez, Blanco, Santolaria (2002): Numerical simulation of the dynamic effects due to impeller-volute interaction in a centrifugal pump, Journal of Fluids Engineering, https://doi.org/10.1115/1.1457452

Trailing edge blowing:

[REF4] Akkermans, Stuermer, Delfs (2016): Active flow control for interaction noise reduction of contra-rotating open rotors, AIAA Journal, https://doi.org/10.2514/1.J053756

Urans Simulations and validation:

[REF5] Stuermer, Akkermans (2014): Validation of aerodynamic and aeroacoustic simulations of contra-rotating open rotors at low-speed flight conditions, 32nd AIAA Applied Aerodynamics Conference, 
https://doi.org/10.2514/6.2014-3133

[REF6] Majidi (2005): Numerical study of unsteady flow in a centrifugal pump, Journal of Turbomachinery, https://doi.org/10.1115/1.1776587

[REF7] Barrio, Parrondo, Blanco (2010 ): Numerical analysis of the unsteady flow in the near-tongue region in a volute-type centrifugal pump for different operating points, Computers & Fluids,
https://doi.org/10.1016/j.compfluid.2010.01.001

4. Also, the introduction should end with a structure overview of the manuscript.

5. In section 2: the authors should mention which blade geometry is used for the reference (or add a citation). This is important with respect to repeatability.

6. One geometry is referred to as "prototype" is ill chosen, in my opinion it would be better to denote this geometry as "reference".

7. Also in section 2: was the design flow rate Q for all four cased the same, or was there a change. It is, to my opinion, important to make a comparison at the same flow rate. Maybe somewhere the authors stated this in the document (and i over-read it), but it needs to mention this more explicitly, also in the beginning of the paper.

8. Equation 2: i think the subscript "psd" is rather ill chosen as it is commonly used for "power spectral density".

9. Figure 9 ( and in fact several other figures): the figure is too small and should be improved as I cant ready the numbers or letters.

10. Line 347: the statement "which proves the accuracy of CFD results" is rather strong and should be reconsidered (or more proof must be added to substantial this).

11. Section 3.2.2: I think the experiments are rather described in a minimal way. The authors need to supply some more info or add a reference to a paper where it has been published.

 

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 3 Report

The paper is well-written and clear.

The topic is gaining of interest since centrifugal pumps are involved in many applications in our daily life.

 

Please proofread the test, sometimes some grammar corrections are needed. Please make sure all the symbols in the text are in cursive.

 

2. Model and numerical methods
3. 1 seems to be cut on the right side.
4. The authors do not describe neither the turbulence closure nor the wall treatment.

 

3. Results
4. The authors should indicate the blade inlet and outlet angle in table 1.
5. Is the point investigated by the author the best efficiency point?
6. Why do the authors do not show the effect of the trailing edge modifications close to the volute tongue? It obvious that far from the volute tongue, the pressure fluctuations are less intense.
7. Since the authors propose a cut on the pressure side, which is the effect of these modifications on the Euler head? How does this worsen the slip factor phenomena?
8. Page 9 “obtains”.
9. Page 9 line 242, maybe do the authors mean figure 11?
10. Figure 11, To get rid of the volute influence, the authors can show the data averaged on multiple rotations (see for instance, Design and CFD performance analysis of a novel impeller for double suction centrifugal pumps, Nuclear Engineering and Design, 2019)
11. Figure 11, it seems in contrast with figure 10. The head seem higher for the modified geometries. Please explain.
12. Figure 12, how the authors justify the decrease of the relative velocity for the model C? The relative velocity should increase at constant peripheral velocity. Please comment.
13. Caption of figure 15, please include the color specification.
14. Why do the author do not investigate the flow angel at the outlet of the impeller?

 

Introduction: the number of references is low. The authors should consider recent works in the literature. There are new geometries proposed to improve the flow uniformity at the outlet of the impeller of centrifugal pumps.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors have sufficiently implemented my remarks and I therefor advise the editor to accept this manuscript for publication.