Cavitation Inception on Hydrokinetic Turbine Blades Shrouded by Diffuser

Round 1

Reviewer 1 Report

The study of cavitation is undoubtedly beneficial, especially in the design of propeller or turbine. This paper proposes a new optimization procedure for the geometric definition of rotor blades free of cavitation applied to DAHT. Comparisons with other models available in the literature are addressed, as well as CFD calculations are carried out to analyze the water vapor pressure formed when the rotor blade is under cavitation. The following are some suggestions for the revision:

1. The research background is not sufficient. At present, there are already a large number of studies on the hydrofoil cavitation. It is suggested to add relevant contents in the introduction section.
2. In the second section of this paper, many equations are listed, but the optimization of the model only gives the optimization algorithm of the hydrofoil chord and twist angle, and there is no specific model parameters of the optimized hydrofoil at the end. Please explain them carefully.
3. In the numerical calculation in the third section of this paper, I only see the geometric model, and there is no content about the mesh division of the model, but there is a mesh independence test in the results and discussion in the fourth section of this paper, which is quite unreasonable. Please add relevant contents.
4. In the 3.3 section of numerical calculation, the author sets the angular speed in the rotation domain as 35 rpm. This paper studies the hydraulic turbine rather than the pump. The moment of inertia should be given and six degrees of freedom motion should be used instead of angular speed.
5. This paper mainly studies the cavitation of hydraulic turbine blades. It is suggested that the author reveal the causes of cavitation combined with the numerical results.

Author Response

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Best Regards

Author Response File: Author Response.pdf

Reviewer 2 Report

There are three problems with this paper:

• Innovation is not outstanding enough. It is necessary to highlight the innovation to increase the novelty of the article.
• There should be a systematic review of the literature. The authors should point out the shortcomings in other literature and highlight the differences between this paper and other literature
• lack new materials or sufficient new materials or information that can contribute to the existing pool of knowledge

In its current form, the paper has no novelty and does not include any significant scientific data

Author Response

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Best Regards,

Author Response File: Author Response.pdf

Reviewer 3 Report

The literature survey could be improved by noting relevant papers, i.e.,:

Pendar, M., Esmailifar, E., Roohi, E., LES Study of Unsteady Cavitation Characteristics of a 3-D Hydrofoil with Wavy Leading Edge, International Journal of Multiphase Flow, Vol. 132, 103415, 2020.

Movahedian, A., Pasandidehfard, M., Roohi, E., 2019. LES investigation of sheet-cloud cavitation around a 3-D twisted wing with a NACA 16012 hydrofoil. Ocean Eng. 192, 106547.

2- Could the authors report grid independence results?

3- Fig. 13 does not bring any data.

Author Response

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Best Regards,

Author Response File: Author Response.pdf

Reviewer 4 Report

The research focuses on cavitation inception on hydro turbine blades with and without a diffuser. The study seems technically correct. The language needs revision although appropriate terminology was applied. The quality and readability of the figures are acceptable. The references cover reputed reviewed papers on the discussed topics however are too limited, particularly in the literature review section.  

The paper can be accepted after addressing the following comments

i. The abstract should include some important results at the end.

ii. The introduction well explains the problem, however, is literature studied is too limited. Only seven references in the section are too less. Add more relevant literature, for instance, you can cite the following paper.

1. Yousaf, B., Qaisrani, M. A., Khan, M. I., Sahar, M. S. U., & Tahir, W. (2021). Numerical and experimental analysis of the cavitation and study of flow characteristics in ball valve. Nonlinear Engineering, 10(1), 535-545.
2. Liu X, Wu Z, Li B, Zhao J, He J, Li W, et al. Influence of inlet pressure on cavitation characteristics in regulating valve. Eng Appl Comput Fluid Mech. 2020 Jan;14(1):299–310.

 

iii. figure 4 should be split into a and b. Provide separate captions for both. The current caption is too short and generalized.

iv. The grid independence test carried out doesn’t appropriately show if the results were even grid-dependent at the start. Also, there should have been at least 5 values to make a better judgement.

v. Images/figures of the mesh should have been included. Cross-sectional view of the mesh showing complete domain and variation of mesh size (if any) along the domain/geometry should also be shown.

vi. Figures 11-13 should be combined into one single figure.

vii. Get the most of CFD tools and provide more contours and graphical results. Such as pressure/velocity contours/ vector images can be added to study their effect. 

viii. What is the significance of figure 13. It can be omitted or replaced by a single statement/text.

ix. Conclusion section lacks mention of significant results. Conclusions drawn should be concise and mention the most novel achievements/significant research gap covered. Each conclusion should be meaningful, gleaned from the most significant results and obvious conclusions such as stating simple facts or generalized phenomena should be omitted.

 

 

Author Response

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Best Regards,

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Now it is accepted

Author Response

The authors are grateful for the valuable contributions.

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors responded to all the comments.

Author Response

The authors are grateful for the valuable contributions.

Reviewer 3 Report

The paper is acceptable now.

Author Response

The authors are grateful for the valuable comments.