Review Reports - Tidal Turbine Apparatus Vibration and Its Effect on Power Production Measurement

Round 1

Reviewer 1 Report

The paper experimentally investigated the effect of vibration and oscillation of an instrumented testing apparatus on horizontal axis tidal turbine rotor energy generation performance. The subject of the research is interesting however, there are some drawbacks in the paper that needs to be modified:

The introduction section is not written properly. In this section, just a description of the testing device is explained. A literature review of similar research by the other researchers should be provided and discussed like the following papers:

https://doi.org/10.1016/j.renene.2020.03.139

https://doi.org/10.1108/HFF-05-2019-0447

Also, please explain clearly the novelty of your research in this section. Furthermore, please provide a brief description of what you did in your research in the last paragraph of this section.

Fig. 1 is not clear. Please name all the different apparatus and sensors that are shown in this figure.
In page 3, what do you mean by “were than obtained.” Please rephrase this sentence “The comparison on the effect of vibration reduction on the improvement of the hydrodynamic performance were than obtained.”
In page 3, please replace the sentence “A propeller dynamometer that 110 has a thrust and torque sensor was used to record the measure thrust and torque. “ with “A propeller dynamometer that has thrust and torque sensors was used to record the measured thrust and torque.” Another thing is that dynamometer is applied for measuring the torque and forces and not recording them. For recording the data, we usually use a data acquisition system and a computer.
In page 4, replace “Table I” with “Table 1”.
In the Materials and methods section, please mention all the sensors you used for test setup along with their measuring range and their precision in a table.
There are also some vague points about your experimental procedure. Please clarify how many times did you carry out each test in order to assure the repeatability of the tests? Also, at least, a sample of uncertainty analysis for a series of data should be presented.
5 and 6 are not clear. Please name all the different apparatus and sensors that are shown in these figures.
In page 8, replace “expanded are ratio” with “expanded area ratio”.

Author Response

Response to Reviewer 1 Comments

Point 1: The introduction section is not written properly. In this section, just a description of the testing device is explained. A literature review of similar research by the other researchers should be provided and discussed like the following papers:

https://doi.org/10.1016/j.renene.2020.03.139

https://doi.org/10.1108/HFF-05-2019-0447

Response 1: A paragraph on literature review was already given (lines 59-64 in the previous version) but we aggree that it is not sufficent. To address this particular comment of the reviewer, a more detaied literature review of about one page is added in the introduction sectdion. Relative references are also cited and added to the list.

Point 2: Also, please explain clearly the novelty of your research in this section. Furthermore, please provide a brief description of what you did in your research in the last paragraph of this section.

Response 2: Thanks. This is a good point. The evidence of novelty was added following the newly added literature review paragraph, in the Introcution section.

Point 3: Fig. 1 is not clear. Please name all the different apparatus and sensors that are shown in this figure.

Response 3: All the compoments of the apparatus were already indicated in the previous version of the manucript. To emphsizely address the comments above, in the revised version, more detailed descriptions are added in the text before the figure.

Point 4: In page 3, what do you mean by “were than obtained.” Please rephrase this sentence “The comparison on the effect of vibration reduction on the improvement of the hydrodynamic performance werethan obtained.”

In page 3, please replace the sentence “A propeller dynamometer that 110 has a thrust and torque sensor was used to record the measurethrust and torque. “ with “A propeller dynamometer that has thrust andtorque sensors was used to record the measured thrust and torque.”Another thing is that dynamometer is applied for measuring the torque and forces and not recording them. For recording the data, we usually use a data acquisition system and a computer.

Response 4: Yes. Agree. All are address in the revised version.

Point 5: In page 4, replace “Table I” with “Table 1”.

Response 5: Thank you very much. It’s done.

Point 6: In the Materials and methods section, please mention all the sensors you used for test setup along with their measuring range and their precision in a table. There are also some vague points about your experimental procedure. Please clarify how many times did you carry out each test in order to assure the repeatability of the tests? Also, at least, a sample of uncertainty analysis for a series of data should be presented.

Response 6: All the comments above were address completely as the following: A table was created to list all the sensors used and their ranges. However, this table is not put in the Meaterial and method section but it is put in the Resutls section instead, because many of the data in the table are tatken from the testing restuls. In the newly added table, a step by step Excel calculation of uncertainty on drag force coefficients for one rotor at varies tip speed ratio was completed and included as well. The expriemental procedure is in fact an ad hoc propeller open-water testing procedure that has been used as a standdard procedure in this facility. The test procedure was also discribed in details in Liu et al. (Liu et al. 2014). Therefore, the test procedure descritpon is enhenced briefly and is refered to the work by Liu at al.. All these above are compiled in one new subsection under the Results section.

Point 7: 5 and 6 are not clear. Please name all the different apparatus and sensors that are shown in these figures.

Response 7: There is only one apparatus, i.e., the topedo shaped object, so called “opensboat”. All the sensors and parts were described in details in Fig. 1a. There is no sensor shown in Figues 5 and 6, because all the sensors are installed inside the “opensboat” to ensure it is waterproof. However, to address the above comment, the mounting configuration for the test set-up is added for both figures 5 and 6.

Point 8: In page 8, replace “expanded are ratio” with “expanded area ratio”.

Response 8: Thank you very much. It is done.

Author Response File: Author Response.pdf

Reviewer 2 Report

The article concerns very interesting experimental analyzes of the measurement of the influence of vibrations and oscillations of research equipment on the horizontal energy generation of a tidal turbine rotor with a horizontal axis. For this purpose, the research equipment was expanded with a number of modern measuring devices. This allowed for the creation of a vibration reduction method and thus a more effective measurement of the tidal turbine apparatus. These types of analyzes provide practical tips for designing, optimizing a tidal turbine rotor to improve vibration, and significantly better measure power factor and drag coefficient. The work is very interesting and suitable for publication in the Journal of Marine Science and Engineering, but needs some improvements:

The introduction should be expanded with a broader bibliographic review, it seems that about the 10 cited items are too poor;
Please correct the units in table 1 (eg: Mpa to MPa);
In my opinion, the more widely tested rotors should be described (more detailed drawings, dimensions) shown in Figure 4;
Figures 5 and 6 should indicate the apparatus used, and then it would be easier to read and verify;
It seems that supporting figures 11, 12, 13 and 14 with tables with measurement results and error analysis would significantly improve the quality of the article.
In my opinion, the summary should be more detailed given the amount of research carried out;
The list of bibliographies should be formatted to the journal's standards and enriched with a broader review, which I wrote about in point 1

Author Response

Response to Reviewer 2 Comments

analyzes provide practical tips for designing, optimizing a tidal turbine rotor to improve vibration, and significantly better measure power factor and drag coefficient. The work is very interesting and suitable for publication in the Journal of Marine Science and Engineering, but needs some improvements:

Point 1: The introduction should be expanded with a broader bibliographic

review, it seems that about the 10 cited items are too poor;

Response 1: Thank you very much. A one page of literature review was added to the Introduction section.

Point 2: Please correct the units in table 1 (eg: Mpa to MPa);

Response 2: Thank you very much. It is done.

Point 3: In my opinion, the more widely tested rotors should be described (more detailed drawings, dimensions) shown in Figure 4;

Response 3: Thank you very much. A paragraph is added to address this comment.

Point 4: Figures 5 and 6 should indicate the apparatus used, and then it would be easier to read and verify;

Response 4: Thank you very much. One paragraph is added to specify the configuration of the test set-up for both figures 5 and 6.

Point 5: It seems that supporting figures 11, 12, 13 and 14 with tables with measurement results and error analysis would significantly improve the quality of the article.

Response 5: Thank you very much. A subsection is added in the Results section, including a newly created table and descriptions for the sensors used, their ranges of measurements and a detailed step-by-step sample calculation of uncertainty on drag coefficients obtained for the rotor with an expanded area ratio of 0.51, at various tip speed ratios.

Point 6: In my opinion, the summary should be more detailed given the amount of research carried out;

Response 6: It is done. One paragraph is added to the Conclusion section to address this comment.

Point 7: The list of bibliographies should be formatted to the journal's standards and enriched with a broader review, which I wrote about

in point 1

Response 7: Thank you for your comments. The format of reference citation is revised.

WRT to the suggestion of increasing refence list, only two more references were added. It is indeed that many experimental studies have been conducted on rotor testing. However, the authors have not seen any similar study to improve experimental accuracy by reducing the vibration and oscillating of the turbine rotor testing apparatus.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Dear Editor,
The paper is properly modified compared to its previous version. I have no further comments and I suggest the paper for publication.