Regenerative Structural Fatigue Testing with Digital Displacement Pump/Motors^†

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Please include more details in the hydraulic diagram of the test system in fig 6: e.g. the cooler, extra hydraulic capacitance, pressure relief valves etc to document the setup.

In figures 10 and 11 (Sankey diagrams), please use identical terms in both diagrams when referring to same component (e.g. DriveShaft & DDPM driveshaft). Furthermore, fig 11 includes components "Actuator" & "plumbing" whereas fig 10 does not. Is this intentional? Could these components be marked also in e.g. fig 6 to specify more accurately?

Please include the information about the measurement system, sensors, power analysers etc. E.g. page 10 line 359 says "measured power from the Danfoss VLT output". How was the power measured?

Include the equations describing how each of the loss component shown in the Sankey diagrams were calculated.

In section 6.3 and also in caption of fig 12, please make sure that the reader understands that the input energy of the conventional system is a calculated approximation, not a measured result. Include also the equation and the initial values used here. Was some kind of loss model assumed for the variable displacement pump?

Author Response

Please see attached file

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The paper ``Regenerative Structural Fatigue Testing with Digital Displacement Pump/Motors'' by William Hugh Rampen, Marek J Munko, Sergio Lopez Dubon and Fergus Cuthill describes the FastBlade -- a facility (developed in Scotalnd), created for testing and certifying turbine blades for marine current turbines. The paper is well written and deserves to be published in Actuators (Section: Control Systems; Special Issue: Actuation and Control in Digital Fluid Power) where it is submitted, after adressing the following minor issues.

 

Font in Fig.7 are significantly smaller than used in the text of the paper. I would suggest to increase it.

 

The legend in Fig 8(a) covers a part of the curve, I suggest to avoid such intersection of the data with the legend.

 

In Fig. 9, the pairs of curves are not distinguishable, I would suggest to increase the resolution of the figure in order to make it visible when zooming in.

 

How the authors plan to perform further studies along this research line is not presented at all. I recommend to discuss it in Conclusion section.

 

It seems line the ``Funding'' and ''Data availability'' sections are forgotten to be modified from the dummy info given by the latex files provided by MDPI.

 

Author Response

Please see attached file

Author Response File: Author Response.docx