Performance of a Propeller Coated with Hydrophobic Material

Round 1

Reviewer 1 Report

The paper entitled "Research on performance of a propeller coated with the hydrophobic material" deals with the experimental and numerical investigation of a propeller coated with the hydrophobic material and a propeller with a conventional surface.

Even though the paper deals with an interesting topic, the following comments should be addressed before the publication:

 

1. There are a lot of misused words and sentences throughout the paper. Professional English reading is required!
2. "for difference scenarios" should be for different scenarios.
3. "experimental and numerical simulation research" should be experimental and numerical investigation.
4. What are "propulsion ratios"? Please correct the term.
5. The following sentence should be revised. "Helal [11] tried to improve turbulence model in CFD simulations of flow on ship propellers."
6. What is "flow drag reduction"?
7. All physical quantities even in the text and tables should be written in italics.
8. What is "the wall shear force expression"? Please revise.
9. Please revise "hydrophobic propeller's flow".
10. Relevant studies regarding the propulsion characteristics should be added in the introduction part. To ensure the completeness of the literature survey, the following references should be added to the manuscript:

Farkas, A., Degiuli, N., & Martić, I. (2021). The impact of biofouling on the propeller performance. Ocean Engineering, 219, 108376., doi:10.1016/j.oceaneng.2020.108376

Farkas, A., Degiuli, N., Martić, I., & Vujanović, M. (2021). Greenhouse gas emissions reduction potential by using antifouling coatings in a maritime transport industry. Journal of Cleaner Production, 295, 126428., doi:10.1016/j.jclepro.2021.126428

 

Those papers should be cited as they are relevant in the current work.

 

11. The mathematical model should be given.
12. vA is the speed of advance or propeller advance speed.
13. The software package must be specified.
14. How are the surface slip conditions incorporated within the software package?
15. A verification study is missing. It should be included in the manuscript.
16. "Hydrodynamic performances of the propeller" should be Hydrodynamic performance of the propeller.
17. It would be preferable to use the symbols according to the ˝ITTC Symbols and Terminology List˝.
18. I recommend the authors to increase the resolution of all figures. The figures are blurry.
19. It is not enough to say that the efficiency is improved. It should be explained in detail.
20. "It can be found that the thrust coefficient and the torque coefficient calculated by the hydrophobic propeller are increased from those of the conventional propeller." Please revise the sentence.
21. What is "speed coefficient"?
22. What is "hydrophobic propeller"? This term does not exist
23. Explain in detail the process of pressure monitoring.
24. The manuscript lacks proper discussion of the results. The obtained results should be discussed in detail.
25. What is "speed field"? It should be velocity field.
26. What does it mean quite different from the experimental results?? The relative deviations should be calculated.
27. It is not enough to say that CFD result assuming 75% surface slip rate is closest to the experimental result. It should be quantified and elaborated.
28. The novelty of the paper should be more clearly addressed and discussed. The authors should compare their research with existing research findings and highlight the novelty.
29. Suggestions for future studies should be added in the conclusion section.
30. The scientific contribution of the paper is completely unclear.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

This paper presents both theoretical and experimental results on the conventional propeller and hydrophobic material coated propeller. The theoretical results obtained in Computational Fluid Dynamics (CFD) by supposing various surface slip rates for setting surface boundary conditions in numerical simulations proved the superiority of the coated propeller regarding the thrust and efficiency.

The paper is original and the research is well conducted. Nevertheless, the paper can be improved and I have some questions and suggestions:

1. How was the mesh generated for the CFD analysis?! Was this automatically generated and uniform?
2. Figure 3 is not clear. What S1 to S4 means?! They are not clearly visualized in Figure 3.
3. How did the authors choose the free slip and non-slip conditions?! Did you make changes to the CFD software?! 
4. The material properties of substrate and coating are not specified: Young modulus, Poisson ratio, etc. 
5. The physical meaning of the parameters defined by equations (1) to (3) should be expressed. 
6. An image of the cross-section with the deposited coating is needed. Was the same coating thickness considered in both theoretical and experimental studies?!
7. The CFD results (Figure 12b) are not close to the PIV experimental results, as we can see green colour in the speed field of the PIV results. Some explanations are requested. This explanation should be included also in the Conclusions section.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

accept

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have successfully addressed all my comments and I suggest the paper to be accepted for publication.

Reviewer 2 Report

The authors responded to all the questions and revised the paper as suggested. I recommend this paper for publication.