Numerical Study of the Induced Shock on the Mixing Augmentation of Hydrogen Counter-Flow Jet in the Supersonic Flow
Round 1
Reviewer 1 Report
This work is a continuation of the work of the authors [7]. In this work, the interaction of the oblique shock waves with a cold hydrogen jet is studied by numerical simulation using a software package FLUENF. The shock wave improves the process of mixing a cold hydrogen jet with a supersonic cold air flow in the combustion chamber. Eight different schemes for the interaction of a shock wave with a hydrogen jet were analyzed. It is shown that two opposite phenomena influence the efficiency of combustion. An increase in the angle of inclination of the shock wave leads to an improvement in mixing, but in this case, the value of the pressure decreases. The analytic hierarchy process is used to evaluate the extent of mixing augmentation by mixing parameters, which provides a decision-making idea for the scheme decision of mixing augmentation.
In this work, the influence of the oblique shock wave on the process of mixing a cold hydrogen jet with a supersonic cold air flow in the combustion chamber was studied. In real conditions, the air temperature is significantly more than three hundred degrees Kelvin. In addition, the temperature of the mixture air – hydrogen increases significantly when hydrogen is burned in the combustion chamber. This will change the flow parameters: sound speed, viscosity and thermal conductivity. Therefore, there may be a large difference between the flow in real conditions and in the conditions considered in this paper. The authors must prove that the picture of the interaction of a shock wave with a hydrogen jet and mixing of hydrogen proposed in this work will not differ much from mixing in a real flow during hydrogen combustion.
Author Response
Dear editor and reviewers:
Thank you for your letter and the reviewers’ comments on our manuscript entitled " Numerical Study of the Induced Shock on the Mixing Augmentation of Hydrogen Counter-Flow Jet in the Supersonic Flow" (ID：aerospace-1891234). Those comments are very helpful for revising and improving our paper, as well as the important guiding significance to another research. We have studied the comments carefully and made corrections which we hope meet with approval. The revisions are noted in the manuscript and highlighted in red. The responds to the reviewers’ comments are as follows.
Point: In this work, the influence of the oblique shock wave on the process of mixing a cold hydrogen jet with a supersonic cold air flow in the combustion chamber was studied. In real conditions, the air temperature is significantly more than three hundred degrees Kelvin. In addition, the temperature of the mixture air – hydrogen increases significantly when hydrogen is burned in the combustion chamber. This will change the flow parameters: sound speed, viscosity and thermal conductivity. Therefore, there may be a large difference between the flow in real conditions and in the conditions considered in this paper. The authors must prove that the picture of the interaction of a shock wave with a hydrogen jet and mixing of hydrogen proposed in this work will not differ much from mixing in a real flow during hydrogen combustion.
Response: The focus of this paper is the numerical study on the mixing augmentation of hydrogen and supersonic incoming flow with the action of shock wave/jet shear layer, which is the preliminary work for the preparation of hydrogen ignition and combustion. Just as the reference [22] in this paper, there are sufficient experimental conditions for cold-flow test using quiet wind tunnel to study the flow characteristics of supersonic flow. The numerical simulation content of this paper can enrich the research on the mixing characteristics of supersonic inflow and hydrogen in the cold-flow condition and provide ideas for the enhancement of the mixing of hydrogen and supersonic inflow. In the scramjet combustion chamber, the inflow air is mixed with fuel, ignited and kept burning, which will significantly improve the combustion chamber temperature. The physical properties of the combustion mixture are different from those under normal temperature. In terms of flow characteristics, the author has added the numerical simulation study and experimental study of hydrogen mixing and ignition under supersonic flow with high enthalpy in the first section of this paper through the reference research, such as references [16,17], which can prove that the study of hydrogen mixing flow in the cold-flow condition has certain significance for the combustion process.
Once again, thank you very much for your constructive comments and suggestions which would help us in depth to improve the quality of the paper.
Kind regards,
Yi Han
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this work, the effect of the induced shock wave on mixing augmentation of fuel counter-flow jet is studied numerically in the supersonic crossflow. Numerical simulations were developed for the analytic hierarchy of process to evaluate the mixing augmentation by mixing parameters.
The paper is clearly written and the results presented are inside the scope of the Special Issue "Jet Flow Analysis".
The manuscript can be published after minor revision (text editing):
1) рage 6 Figure 5 is absent
2) рage 7 line 213: The contour black curve is not clearly visible in Fig. 7b
3) Ñ€age 18 line 436: “Table 6” should be renamed “Table 7”
Author Response
Dear editor and reviewers:
Thank you for your letter and the reviewers’ comments on our manuscript entitled " Numerical Study of the Induced Shock on the Mixing Augmentation of Hydrogen Counter-Flow Jet in the Supersonic Flow" (ID：aerospace-1891234). Those comments are very helpful for revising and improving our paper, as well as the important guiding significance to another research. We have studied the comments carefully and made corrections which we hope meet with approval. The revisions are noted in the manuscript and highlighted in red. The responds to the reviewers’ comments are as follows.
1) рage 6 Figure 5 is absent.
Response：рage 6 Figure 5 has been supplemented and marked in red.
2) рage 7 line 213: The contour black curve is not clearly visible in Fig. 7b.
Response：рage 7 line 213: the contour black curve has been thickened for clearer visualization in Fig. 7b.
3) Ñ€age 18 line 436: “Table 6” should be renamed “Table 7”.
Response：рage 18 line 436: “Table 6” has been renamed “Table 7”.
Once again, thank you very much for your constructive comments and suggestions which would help us both in English and in depth to improve the quality of the paper.
Kind regards,
Yi Han
Author Response File: Author Response.pdf
