Study on Aerodynamic Performance and Wake Characteristics of a Floating Offshore Wind Turbine in Wind–Wave Coupling Field

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper deals with a very interesting and current area. The authors presented the results in a very scientific way, highlighting the main achievements compared to the previous literature. The paper can be accepted, but it is necessary to carry out certain refinements in order to improve the quality of the work and its application for subsequent tests.

It is necessary to review additional literature and recent works in this field and cite works from this and similar fields, such as:

-       DOI 10.1016/j.oceaneng.2024.118061.

-       DOI 10.1016/j.renene.2019.04.134.

-       DOI 10.1016/j.rser.2022.113144. 

Expand the introduction or other chapters with papers in this area.

As it is a very interesting paper, I think that at the end of the introduction of the paper, it is necessary to state specifically what the main contribution of the paper is and how this paper differs from similar papers in this field? What are the main reasons, i.e. why do the authors think that this paper should be published?

Increase the number of references in the paper based on the given remarks.

It is necessary to indicate whether the repeatability of the results was ensured in the experiment, that is, how many times the experiment was repeated in order to obtain the mean values ​​of the observed quantities.

It is necessary to state whether the obtained experimental results can be described by some of the mathematical models and methods, i.e. whether it is possible to predict with some mathematical model the obtaining of certain quantities and parameters for other experimental conditions, primarily at other wave heights and at other times of wave appearance, and not only for precisely defined wave height values ​​of 4 m, 6 m, 7 m and 10 m and wave appearance times of 10 s, 12.5 s and 15 s. 

Bearing in mind that the paper describes a floating turbine for the production of electricity, it is necessary to give a brief description of the method of transmission of electricity to the transformer plant on the coast, an estimate of the losses of electricity during the transmission of electricity from a floating turbine with a generator.

Bearing in mind the topicality of the mentioned topic, some limit values ​​of the wave height up to which the mentioned turbines can be used should be given, as well as ways of protecting the turbines in the event of storms and strong storms.

In the concluding remarks, it is necessary to clearly state whether the obtained results confirmed the expectations and assumptions, that is, whether there were deviations or completely opposite results from the expected ones.

Consider the possibility of describing the way of placing these floating turbines in the sea, the minimum distance between individual turbines and the possibility of connecting power cables for the transmission of electricity from several floating turbines, as well as the way of forming the field of floating turbines.

Based on the analysis and discussion, expand the concluding considerations, especially in terms of further research in the field of application and other experimental conditions, perhaps the application of the mentioned methods and techniques for predicting the drop in nominal generator current and power with a change in wave height and wind speed, as well as changes in the obtained installed power of the generator floating turbines with a change in turbine geometry. Look at the possibilities to comment on the reduction or increase in the costs of exploitation and maintenance of turbines by applying the solutions mentioned in the paper in relation to the current solutions of floating turbines used in exploitation.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This paper presents a study on the wake characteristics and aerodynamic performance of a 5 MW floating wind turbine. The authors have used dynamic fluid body interaction (DFBI) and overset grid technology for their investigation. The paper presents background on the topic followed by numerical configurations, results, and detailed discussions on various aspects of the wind turbine characteristics. 

Overall, the paper is well-written. However, the contribution itself is average because the study's scope is limited. Also, what about the previous investigations on the wake characteristics of floating wind farms? The authors did mention at the end of the introduction section that there are fewer studies on the near-wake turbulence, vortex band evolution, and far-wake characteristics of the floating horizontal axis wind turbine under the pitch motion. Yet I am not sure about the significance of the contributions (some more explanation on the original contributions in the introduction section would be helpful). 

Finally, the authors claim in the final paragraph of the introduction section that there are five sections in the paper. However, in reality, there are only four sections. 

It is requested that the authors make minor revisions based on the above discussion. 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

1-It is better to add some numerical results, if exist, to the abstract.

2- The authors should add reference to equations 1-6.

3- In Fig.2, what is meant by 'Vave'? I think it is 'Wave'.

4- The authors didn't include any grid size analysis to obtain the optimum size.

5- The authors only refer to the independence of the grid without any recent information. Please, add more details.

6- The validation section didn't contain error analysis. What is the error between the present work and NREL FAST? Please, add it in a table form.

7- What are the numerical values of the boundary conditions?

8- The authors didn't include analysis at different blade sections. For example, r/R=0.9, 0.7, 0.5 and 0.3.

9- The details in conclusions should be better transferred to the discussion section. The conclusion remarks should be concise.

 

Comments on the Quality of English Language

Minor editing of English language required

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

the authors are the answers to all remarks and suggestions

 

I suggest that the paper be accepted for publication