Aerodynamic Effects of a Wing Surface Heat Exchanger

Round 1

Reviewer 1 Report

Dear Authors,

1.) Introduction section can be in detail to clearly explain the literature gap addressed in the paper. More literature could be added.

2.)Since the effect of multiple parameters are analyzed, it will be effective if you summarize it in a quantitative way in the conclusion.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The paper is well-written and well-structured, and the numerical simulations and results analyses seem to have been carried out carefully.
I'd recommend the paper for publication after addressing the following.

Can the Authors specify and comment on the grid size and grid resolution? A RANS approach cannot resolve the smallest turbulent scales, still, it is surprising that the numerical solvers and experimental results match so well (fig 6). It seems like turbulence plays a negligible role as long as the boundary layer is attached. However, separations can occur, even triggered by the heating of the wing surface. I think it would be good to comment on the effects of possible BL separations or to stress that the presented results are only preliminary for large angles of attack configurations. In this sense, the study mainly addresses cruise conditions. Regarding this, the Authors mention in the abstract that "the aerodynamic efficiency of the wing improves in cruise conditions". This claim seems not to be supported by the results, which instead point to a general deterioration of the aerodynamic performance.

Minor comments
line 4: dissipated and transported would be preferable to "dissipated";
line 152: "Turbulence intensity 0.1". How is that defined here?

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Overall comments:

(1) The paper is to study the application of a wing surface heat exchanger. However, the wing surface heat exchanger is not specified in the context.

(2) The paper is to study the hybrid-electric aircraft based on the ATR 72-600. However, if the amount of heat rejection is enough for the design is not specified. 

 

Comments on Title:

(1) The title puts stress on a wing surface heat exchanger, which is not explictly described in this paper. It is suggested to modify the title for a better describtion of the main content of this research, e.g., aerodynamic effects of the heated wing boundary layer.

 

Comments on Abstract:

(1) Introduce more about the resesarch methods of this study.

(2) Put quantitive results in the abstract.

 

Comments on Chap 1 Introduction

(1) Line 19: Are you suggesting the (hybrid-) electric powertrain is less efficient? Please specify the reason to use heat exchanger for the (hybrid-) electric powertrain compared with gas turbine powertrain.

(2) Line 25: To use the fuel as coolant, what if the fuel level is low? There seems to be problems to maintain the function of the electric components.

 

Comments on Chap 2 Hybrid-Electric Regional Aircraft with Wing Surface Heat Exchanger

(1) The subtitle of chapter 2 can be modifed to eliminate the wing surface heat exchanger, which is not really introduced.

(2) Figure 2: airfoil 45015 is not appeared in Figure 3. Why do you need to display it in Figure 2?

(3) Figure 3: the L/D of the airfoil at cruise condition (CL=0.45) is around 30, which looks lower to the reviewer's knowledge. Can you explain the reason? Are there any limitations on the methods applied?

(4) Use present tense. 

 

Comments on Chap 4 Simulation Setup

(1) Line 257: The information of the propeller type is not useful in this study (?)

(2) Table 1: It is not clear to the reviewer why the author choose these non-uniform Tw points 0/25/50/75/100/120/140/160/200/300. Please specify.

(3) Table 2: Why the thrust of the prop is given rather than the slipstream speed?

(4) 4.3 Study Setup: Which solver are you using for this study, SU2 or OpenForm?

 

 

Comments on Chap 5 Uniformly Heated Two-Dimensional Airfoil

(1) Please use a sketch to illustrate the uniformly heated 2D airfoil and the mesh for CFD calculation.

(2) Figure 13: please adjust the legends position and size so that the plots are not overlapped.

 

Comments on Chap 6 Heat Patches on a Two-Dimensional Airfoil

(1) Please modify the sketch to include the mesh for CFD calculation.

 

Comments on Chap 7 Uniformly Heated Three-Dimensional Unswept Wing Section

(1) Please use a sketch to illustrate the uniformly heated 3D wing and the mesh for CFD calculation.

(1) L/D ratios are mentioned many times. However, there is no L/D plot in this chapter.

 

Comments on Chap 8 Conceptual Aircraft Design Implications

(1) This study is meaningful for the airfoil and wing section. It is not meaningful for the application of the regional HEP design.

 

Comments on Chap 9 Conclusion

(1) Please conclude this paper with quantitive results.

 

Comments on References

(1) References 16 is not accessible for the reviewer, which makes it difficult to understand the configuration.

(2) Please check the reference format with journal requirements.

 

Comments on Abbreviations

(1) Please check & include all the abbreviations in the list

 

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors have addressed all my comments.