An Efficient Method for Computing the Power Potential of Bypass Hydropower Installations

Round 1

Reviewer 1 Report

This article has demonstrated that a theoretical analysis of the achievable performance in floating or bypass hydropower installations allows designers and operators to answer questions of practical importance in a computationally-efficient way. The paper is well organized, the method is clearly elaborated, and the results support the theory quite well. I recommend the paper be published with only a tiny comment as shown below.

This paper demonstrates that a theoretical analysis of the achievable performance in floating or bypass hydropower installations allows designers and operators to answer questions of practical importance in a computationally-efficient way, through using a low-resource CFD model.

The strength of the paper lies in verifying that the low-resource model is competent to predict the performance of the turbine, which significantly improves the prediction efficiency. The object of this paper is quite interesting, and the structure is well organized.

Some comments:

1. In page 2, it may be better to clarify why a water vortex power plants has been chosen for the study.
2. Why the response time is of the order of 45s, needs more explanation.
3. The simplification process towards the low-resource CFD model needs clarification. For example, why the turbine can be replaced with a cylindrical outlet in the upstream channel and a disc-shaped inlet in the downstream channel, etc.
4. In Figure 3, it may be better to show the color bar so that more information can be presented.

Other comments:

1. 1. In line 57 “Observation of the dynamics of the installation in Dresden during testing reveals that its behavior is not simple.” may require a citation to existing references to verify.
2. It seems that the indentation in the first row of the end paragraph in each section is neglected. Please check if it is suitable.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

In this paper, a numerical study has been conducted to investigate performance of a hydropower device by simplifying a complete CFD simulation.

The reviewer thinks that the presentation and quality of the paper is good. However, there are some important points that needs to taken into consideration. Please see below comments:

1. The explanation of the model is quite enough in Section 1 and 2; however, a very small number of papers have been discussed in the paper although reference numbers are quite high. For example, in the first page (from line 18 to 38) you have already 16 citations; however, they are the citations for general information. So, I highly recommend enhancing the literature review by discussing other works.

2. Figure captions are too long. The details could be explained in the text.

3. If possible, please provide the length of the channel in Figure 1.

4. More detail about the boundary conditions, e.g. inlet, outlet and walls should be provided. The reviewer also suggested giving more details about the solution procedure.

5. I believe a grid and time independence studies are needed. The authors stated that 2.6 million cells have been used along with 0.02s time step size. These studies will enhance the quality of the paper.

6. The reviewer suggests more parametric study, for instance, mass flow rate or height, etc.

7. Could you please provide what is the highest difference between theoretical and numerical results in the validation ?

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Thank you for answering my comments.