pyCycle: A Tool for Efficient Optimization of Gas Turbine Engine Cycles

Round 1

Reviewer 1 Report

The authors claim that the "objective of this research effort was to investigate the development a new thermodynamic cycle analysis code, called pyCycle, to address this limitation and enable design optimization of these new vehicle concepts". How aircraft-engine integration problems are addressed in the code? Please explain.

Figure 1: there are many more cycle tools available. E.g. Proosis, Turbomatch, GasTurb, GSP etc. Where they stand for?

The whole process for the cycle calculation needs clarification. E.g. Page 11: equations 7 to 10: it is not clear what are the inputs. How the PR or component efficiencies are known in an off-design step? Any use of component maps?

Figure 11: The legend does not comply with the plot (i.e. lines are missing).

I think that the paper is quite extended for a journal article. I would consider splitting it into 2 major parts: the first one about the tool for the cycle simulation and the second for the optimization.

Author Response

Thank you for your feedback on our paper.  We addressed your comments by making the following changes, which are highlighted in the revised manuscript.

To address your first comment about how aircraft-engine integration is enabled by this code, we included a sentence in the introduction (lines 146 to 149) with several references to recent research on boundary layer ingestion concepts and coupled propulsion-thermal management systems which have been enabled by this code.  We feel the details of those research efforts are beyond the scope of this paper, but agree that providing references to those publications directs the reader to further information on the application of this code in that context.

In Figure 1, we updated the history to include several of the tools you mentioned.  We have limited experience with these tools, so we did our best to place them within the appropriate era based on published literature.  We recognizes that there are many other cycle analysis that have been used over the years that could be included on this figure, so we tried to select a representative sample codes based.

For the cycle analysis process, we made several revisions to hopefully address your comments.  First, we clarified in Figure 3 what is inputs and outputs from this simple compressor example (lines 385-388).  Second, we revised the wording at the end of the calculations (line 418-421) to emphasize that the compressor example provide was a demonstration that did not include all calculations in the full code.  The actual code includes calculations for performance maps, bleed flows, etc. and we direct readers to the source code and documentation for the full calculations for each element.

For Figure 11, we revised the line thicknesses for several of the cases to try to emphasize that the results were identical.  We also added to the caption to note that many of the optimizations produced identical results and that the lines were coincident.  This was mentioned in the text discussing the figure, but adding it to the caption will further clarify the results for the reader.

Lastly, we agree that the paper is extended for a journal article.  Despite its length, we felt it was best to show the method, tool and the example optimization together to have a self-contained, rigorous document.  Furthermore, this document was indented for two audiences, those more familiar with cycle analysis and those more familiar with MDAO.  We felt it was best for this special MDAO edition of Aerospace to provide a longer, but more encompassing paper to provide valuable information to both audiences.  

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper was very well-written and its scientific contributions are evident. I highly recommend the paper to be accepted without any revision.

Author Response

Thank you for your feedback on our paper.