Please find my review in the attached document

The topic of the article is the interaction between vortex generators and rotational augmentation on wind turbine blades. The manuscript is based on a numerical analysis performed with RANS simulations.

There is a lot of literature available both about rotational augmentation and vortex generators. However, the interaction between them has received until now little attention in spite of its relevance for the design of wind turbines. The article contributes therefore to an important subject.

Furthermore, the approach followed for the analysis of the rotational augmentation effect has been used in just a few publications in the past and it presents some advantages like the lack of need to estimate the angle of attack. This can be regarded as a new way to study an old problem.

The article will be of interest to a broad audience interested in the blade aerodynamic design of wind turbines.

The methods used are in general well described. However, as stated in the comments below, I do not think that the RANS method is the most appropriate approach for the study of separated flows.

Both the title and the abstract are adequate and clear enough. The abstract also includes a good summary of the most important results.

The description of the state of the art is detailed enough and the authors credit the ideas from previous works of the literature.

The conclusions of the work seem to be plausible and backed up by the obtained results.

The paper is in general well written, but it is quite repetitive due to the very rigid structure of the manuscript, in which the same types of results are always presented individually for different vortex generator topologies.

One of the major strengths of the article is the high-quality visual representation of complex physical phenomena (e.g. Fig. 1 and Fig. 8). This type of diagram is unfortunately rare in the literature, but very helpful for understanding the main ideas of the article.

Due to the very repetitive analysis of the results (as stated above), the article is actually too long and rather tedious to read.

All in all, I recommend the article for publication with the following revisions:

Major comments:

- The article is too long. Please try to present the results in a less repetitive way. It is quite hard to compare the results of the different configurations since they are presented separately. A more compact description of the results, focusing on the differences between the different VGs configurations would be highly appreciated.

- It is well known that RANS has strong limitations for the analysis of separated flows, which is precisely the topic of this work. A Detached Eddy Simulation should actually be better suited for this kind of application. Please explain your reasons for using RANS and discuss the reliability of the results in this regard. If possible, I would recommend repeating at least some of the simulations with DES and comparing the results. This would help to assess the reliability of the RANS simulations.

- A grid independency study is missing. I suggest repeating at least some of the simulations with a finer grid in order to see how that influences the results.

- The article describes in different places (e.g. line 353) how the radial flow leads to rotational augmentation, which in turn increases the lift. But what is the effect on the drag force? The fact that the tangential force is increased does not necessarily imply that the rotational augmentation does not have any influence on the drag.

- The conclusions section is in my opinion still a bit weak: what are the practical implications of this work? How can industry and science benefit from the main findings of the manuscript? Is it possible to give recommendations about the use, installation and limitations of VGs?

Minor comments:

- The authors claim that the VGs can lead under certain conditions to a torque increase of 3.28%. I think that it makes no sense to give results with two decimal positions when the uncertainty of the simulations is obviously much larger. I suggest stating „a torque increase of approximately 3%.

- Line 60: I do not really understand this sentence. Mass conservation should apply. I suggest some rewording for explaining the idea.

- The description of the CFD model is not detailed enough. Which type of discretization is used for time and space? Which are the boundary conditions? Some information on the computational efficiency of the model would be appreciated. How long did the simulations run with how many cores?

- The size of the VGs is given meters, which in my opinion is quite difficult to read. I recommend giving it in mm.

- Line 296: I can not see the root vortex composed of two-counter rotating vortices. I suggest marking it as clearly as possible in the figure.

- Line 326: This is an interesting interpretation of the role of root vortex. Can you relate it to Fig. 8 or any other visualization?

The paper describes a very detailed RANS analysis of VG and rotational effects and their interaction on a 2MW WT blade. The topic is relevant and interesting and the analysis is more thorough than existing studies. The discussion could be improved in terms of depth, insight and presentation. Please find detailed comments in the attached file.