Experimental Study on the Aerodynamic Performance and Wave Energy Capture Efficiency of Square and Curved OWC Wave Energy Conversion Devices

Round 1

Reviewer 1 Report

I have reviewed this submission from Li X. et al on "Experimental study on the aerodynamic performance and wave energy capture efficiency of square and curved OWC wave energy conversion devices". Seen from the text, the motivation of this work is to compare through physical model tests, in terms of the relative wave height and pressure in the chambers of square and curved oscillating water column (OWC) WECDs and to obtain one with the best performenace. The results are interesting and provide good support to the conclusions. However, there are several issues need to be addressed before satisfying the publication standard. I suggest minor revision before publication.

1.How to dissipate the wave at the end of the physical tank, and the size of the block needs to be supplemented.

2.The units in Table 2 should adopt the international system of units, and the unit of opening width and opening height should also be changed to meters.

Author Response

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Reviewer 2 Report

The paper analyzed the operational performances of the chambers of square and curved WECDs through model tests. The aerodynamic performance and WECE of the square and curved WECDs at different incident wave heights, opening lengths and widths of the chamber, chamber areas, and chamber volumes are compared. The experimental data is well presented, and the conclusions are well supported by the material. Here are some comments:

1. In table 1, the wave pressure and time can be removed since no data is given for these parameters.

2. It may be better to compare the performance of the oscillating water column WEC studied in this paper with those in other papers.

3. The conclusion part, together with the abstract part, should express more concisely the experimental findings, and focus on the most significant scientific findings. 

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

This article presents the results of an experimental study comparing two different OWC front wall shapes: (1) square and (2) curved. For each device, tests were conducted for various incident wave height and period conditions, opening length and width (also aggregated into a single area parameter), and chamber volume. The paper is easy to read and contains much valuable data. 

 

Technical Suggestions

1. On lines 116 and 117, the authors justify the assumption of incompressibility. On lines 204 and 205, it is mentioned that the air was compressed. The incompressibility assumption was used later in the efficiency calculations, where the air density is assumed constant. This may be fine for the pressure range of interest. At a minimum, the inconsistency in the text should be addressed.
2. The dip in most of the plots at T = 1.8 s (see Figure 6, for example) is mentioned in the text. I’m accustomed to seeing smoother results. For example, He, Fang, Mingjia Li, and Zhenhua Huang. "An experimental study of pile-supported OWC-type breakwaters: energy extraction and vortex-induced energy loss." Energies 9.7 (2016): 540. Including a physical explanation of the effect in addition to the existing observations would be beneficial.

 

 

Editorial

1. The results flow is divided into two parts (1) measurements, ending in Figure 7, and (2) performance, starting in Figure 8. This results in repeated introductions to each test case. One suggestion is to reference the measurement Figure in the performance Figure and vice versa. For example, Figure 8 should reference Figure 3 in its caption, and Figure 3 should reference Figure 8. That will allow the reader to find the correct comparisons.
2. The figure captions are all very similar, regardless of the varied quantities. The captions should be unique to each figure by briefly mentioning the constant and varied parameters.
3. Figure 8b, H=4cm, appears to be the data of the H=8cm case. 
4. Line 252 should not be indented
5. Line 379 “performances” should be “performance”
6. Line 429 “offices” should be “orifices”
7. I was not able to find the reference shown on line 460
8. All the plots show the horizontal axis labels as T/s. Is the period normalized, or should they b Wave Period (s)

Author Response

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Author Response File: Author Response.docx