Analysis and Experimental Research on Efficiency Characteristics of a Deep-Sea Hydraulic Power Source
Nigel Johnston
Round 1
Reviewer 1 Report
This paper is a careful study of the influence of pressure on the performance of hydraulic systems in undersea applications. The main contribution is to bring together information from disparate sources and use this information to synthesize an overall system efficiency analysis. The oil-submersed motor evaluation requires detailed finite element analysis. The hydraulic system analysis does not. The Barus equation is used to model the pressure-viscosity relationship with experiments used for fitting. The analysis is validated with careful experiments. The paper is well written. There may be a few small errors. I only detected one. On line 625, "Pross" should be "Process".
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
This is an interesting and relevant investigation of the effect of ambient pressure on hydraulic system performance. However some clarifications are needed, particularly on the effect of temperature.
Use of a throttle valve to simulate the load may give misleading results, as the resistance of the valve will vary with ambient pressure.
Temperature variations may have a very significant effect on the results, as viscosity is strongly dependent on temperature, generally more so than on pressure over the ranges considered here. It is necessary to show the variation of temperature over all of the parts of the pressure variation curve in figure 27, and this should be done in the main body of the paper, not an appendix. Without this it is not clear if the variations in figure 30 are caused by ambient pressure (as claimed) or by temperature. The plots in Appendix A only show variations over small parts of the test, and it is not clear which parts. A 60 minute holding stage is referred to in figure A1, but this does not seem to correspond to the 115MPa stages in figure 27 which appear to be about 180 and 120 minutes long.
The English is generally clear, but proofreading and some corrections are needed. For example:
Line 148: ‘normal is pressure’
Line 381: ‘quantitative’ should be ‘positive displacement’
Line 625: ‘Pross’ is not a word.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
The comments on the previous version have mainly been addressed satisfactorily. I just have some minor suggestions.
Line 168: Figures A1 and 29 are referred to here but these figures are much later in the report. Figure 29 should be renumbered and placed here, at the point where they are first referenced.
The Appendix is now short, it is not referred to in the main text, and its context and purpose is not clear. Maybe it should be inserted into the main body, in section 2.2?
Line 588: "keep the motor speed and ambient pressure unchanged" would be better as "the motor speed and ambient pressure are unchanged".
has a candidate who has obtained a scholarship from his home country to cover overseas fees (not stipend) for three years. The project proposal is attached, together with the conditions of his scholarship which look reasonable to me. The proposal fits the strategic priorities of low carbon and sustainability, and links in with an impact story with David Coley for the next REF. We could support it with URSA funding of about £50k to cover stipend for three years. We could stretch to 3.5 years as is normal, but the scholarship only covers fees for three years and we will have to check if this is allowed. If it is allowed I suggest that we do this.
has a candidate who has obtained a scholarship from his home country to cover overseas fees (not stipend) for three years. The project proposal is attached, together with the conditions of his scholarship which look reasonable to me. The proposal fits the strategic priorities of low carbon and sustainability, and links in with an impact story with David Coley for the next REF. We could support it with URSA funding of about £50k to cover stipend for three years. We could stretch to 3.5 years as is normal, but the scholarship only covers fees for three years and we will have to check if this is allowed. If it is allowed I suggest that we do this.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
