Feedback on Ch5 paper based on CFD-RANS

It is encouraging that you took the initiative to write this journal manuscript, but it needs a lot of work as I am afraid that in its current form it is likely to be rejected. Besides the style that needs fixing, my main concern is the claim that the CFD gives more credibility the BEM-Park model, which is not correct according to Fig 7. This may be fixed by the following steps:
1. Numerical methods:
Eqs (1) to (6) are not numerical methods but definitions. They should appear under Section 2, where you should also add the definition of C_P for the dual rotor (you can join expressions together to reduce the number of equations, e.g. the definitions of dual rotor TSRS are all in one equation separated by commas). Instead there should be a description on the BEM-Park model with an explicit expression of the velocity deficit in Park's model under numerical method. Such description appears in your PhD thesis and you can use it as it is not a journal publication. The CFD paragraph can be broken to 2-3 paragraphs and must also include a paragraph how the dual rotor configuration is modelled.
2 Grid convergence:
You should also show convergence in C_P (coefficient of power). It can be for a certain TSR.
3 Single rotor case:
What is the C_P for TI=15%? If it is much reduced, it can explain the better velocity recovery behind the rotor. You should look for a ref where they also got reduced C_P from RANS as compared to other results when the blade is mostly in stall in order to better support the reduced C_P from RANS at theta_T=-2 degs.
4 Dual rotor case:
Fig 7 is a mess. I do not understand the short lines from RANS. Are they for dual rotor where the front rotor is at theta_T=2 degs and the rear rotor is at theta_T=-2 degs? If yes, then something is very wrong with the RANS calculation, because by Fig 6a RANS gives positive C_P for the rear rotor when TSR<6. In IJET paper the front rotor's C_P line was added to the graph of the dual rotor C_P lines in order to show the benefit of using a dual rotor configuration. You can use the same approach for Fig 7 or even better and just show the lines for a dual rotor configuration. The IJET BEM-Park results are for dual rotor with the same RPM (front and rear) which means the same TSR if normalised by the free stream velocity U_infinity or the same TSR which means the TSRs of Eq (4) and (5) for the front and rear rotors respectively.
5 Park wake model evaluation:
By Fig 9(b) it seems that TI=15% case fits pretty well the Park model with k=0.04 (unlike what is written in the text). Can't we get a new k to fit the line of TI=1% and repeat the calculation of BEM-Park model? It will also be of great interest to see the radial distribution of the velocity recovery, i.e. to integrate the velocity over the azimuthal direction. That can be incorporated into the BEM model in a future calculation
6. Journal:
I saw that you used Elsevier LaTeX format. What journal do you have in mind?
7. Authors:
I saw that you added Jiahuan as a author which is fine. However, please note that SEMS regulations require a SEMS academic to be a corresponding author (there can be more than one corresponding author) particularly when SEMS has put some funding into the project, unless there is a unique reason not to.

My further specific comments are in the attached.