Research on Computational Method of Supersonic Inlet/Isolator Internal Flow

Round 1

Reviewer 1 Report

1) In the introduction, the authors review some experimental results. It is not clear how is this review connected to the present study. It seems that this part of the review is not needed.

2) The authors did not introduce the abbreviations such as SWTBLI. All abbreviations must be introduced and properly identified.

3) In Section 2 (RANS Computation Model), the authors did not introduce all symbols.  Authors must identify all symbols correctly. Furthermore, authors use RANS equations yet they do not identify whether they used correctly averaging to account for density fluctuations. Moreover, in equations 4, 5, and 6, authors use symbols without any identification of their meaning. Is ideal gas assumption used in their work. What about heat flux? What is the dependence of viscosity, heat conductivity, etc. on temperature. What is the relationship between energy and temperature? This is all missing. Therefore, the equations set is incomplete and readers cannot repeat the computations to independently verify results.

4) In Section 2.2 authors do not identify the meaning of symbols again. What are the Greek delta and nabla symbols in equation 7? An educated reader might try to guess but this is not an acceptable practice in scientific publications. Also, here is the reference for the limiter in equation 8?

5) Another example of imprecise notation is evidenced in equation 9. What is the index k?

6) Authors in Section 2.3 state that the time integration can be combined with some acceleration technique. Did the authors ended up using the acceleration technique? If yes, then which one?

7) How is mesh slenderness in Section 2.5 defined? There is very little information on mesh design and mesh size. It is completely unclear if this remark is for 1D shock tube or 2D simulations.

8) Why was only a 1D shock tube test performed to assess the accuracy and validate simulations? Was the shock tube inviscid? If yes, how does this validates CFD solver that involves RANS model?

9) Density fluctuations become very important in supersonic and hypersonic flows. How are those fluctuations have been captured in DES and LES? If authors consider them unimportant, they should justify their model and assumptions.

10) What are the inlet turbulence conditions that were used for RANS, DES, and LES? The authors do not describe those conditions at all.

Overall the paper must be significantly improved in order to be considered for publishing.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The paper describes the implementation and validation of different numerical schemes for the simulation of compressible (non-reacting) flows. I suggest the following modifications to improve the readability of the paper:

• In the introduction (Line 25 and 29) the authors write about subsonic conditions and subsonic diffuser in a SCRAMJET engine: the SCRAMJET engine is fully supersonic, the flow is not decelerated to subsonic conditions
• Eq. 6: if a non-inertial rotating system is considered both the Coriolis and the centrifugal force should be considered, not just the Coriolis force. Furthermore, the centrifugal force should appear also in the energy equation
• The authors should introduce the references to the different numerical fluxes cited in the paper (AUSM, Roe,...)
• The authors should define all the symbols (DELTAij, TRIANGLEij,...) in Eq. 7, expecially for non-uniform grids 
• The authors should define all the symbols in Eq. 9 and 10, clarifying how the reconstruction is performed in multidimensional problem
• Same comment for MP method: explains how to generalise to multidimensional problem
• Line 188: The expression "grid slenderness ratio of the mainstream area" is not clear. Do the authors refer to the aspect ratio? 
• Lines 293-296: the authors comment the 3D effects by referring to Figure 10. However, Figure 10 shows 2D results. Do the authors intend to refer to Figure 12?
• Figure 13 is never cited in the text. Furthermore, it is not clear the z position at which the pressure profile is measured in the 3D simulation
• The authors should report the inlet boundary conditions used for the SST model
• The Section on DES/LES should be improved: the authors report just a visualisation of an instantaneous field obtained by DES. The results from LES are missing. The authors should include more results on LES/DES simulations (average Mach field, average pressure distribution, ...)
• Line 107

Author Response

Please see the attachment.

Author Response File: Author Response.docx