Document Type : Original Article


1 Department of Mechanical and Aerospace Engineering, Ferdowsi University of Mashhad, Mashhad,Iran

2 Department of Mechanical and Aerospace Engineering, Ferdowsi University of Mashhad, Mashhad, Iran


This research delves into the intricate realm of supersonic inlet design for ramjet engines, honing in on the critical aerodynamic considerations and optimization of performance factors. At Mach 2.5, the study meticulously scrutinizes pivotal design parameters, including the placement and number of inclined shocks, cowl-lip positioning, throat area, spike location, and diffuser length. Computational fluid dynamics simulations are harnessed to unravel the intricate flow dynamics and assess the proposed inlet geometry's performance.The findings reveal a nuanced relationship between back pressure and shock wave positioning, where increasing back pressure initiates a shift in the shock wave, impacting the flow state. The paper delineates this transition, emphasizing the pivotal back pressure range of 300,000 to 350,000 pascals, where optimal shock wave alignment corresponds with design parameters, achieving a supercritical state.However, elevating back pressure beyond this range triggers a sub-critical state and mass flow overflow as the shock exits the throat.the study explores various performance metrics, encompassing drag coefficient, distortion coefficient, mass flow ratio and total pressure recovery under varying back pressure conditions. The outcomes underscore the merits of higher back pressures, which mitigate drag coefficient and distortion while amplifying TPR.In the sub-critical state, MFR diminishes due to shock wave displacement beyond the intake opening.This research illuminates the intricate dance of aerodynamics within ramjet engine inlets and underscores the paramount significance of optimizing inlet geometry to unlock heightened performance. It effectively encapsulates the essence of the full article, enticing readers to embark on a deeper exploration of this crucial area of aerospace engineering.


Main Subjects

[1]      Yadegari, M. and M. Jahdi, Capturing of Shock Wave of Supersonic Flow over the Bump Channel with TVD, ACM and Jameson Methods. Iranian Journal of Mechanical Engineering Transactions of the ISME, 2021. 22(1): p. 108-126.
[2]    Yadegari, M. and M. Abdollahi Jahdi, Shock capturing method by numerical dissipation control on symmetric airfoil. Journal of Solid and Fluid Mechanics, 2016. 6(1): p. 285-304.
[3]  Yadegari, M. and A. Bak Khoshnevis, Investigation of entropy generation, efficiency, static and ideal pressure recovery coefficient in curved annular diffusers. The European Physical Journal Plus, 2021. 136: p. 1-19.
[4]   Yadegari, M. and A.B. Khoshnevis, Entropy generation analysis of turbulent boundary layer flow in different curved diffusers in air-conditioning systems. The European Physical Journal Plus, 2020. 135(6): p. 534.
[5]   Yadegari, M. and A.B. Khoshnevis, Numerical study of the effects of adverse pressure gradient parameter, turning angle and curvature ratio on turbulent flow in 3D turning curved rectangular diffusers using entropy generation analysis. The European Physical Journal Plus, 2020. 135(7): p. 548.
[6]   Yadegari, M., An optimal design for S-shaped air intake diffusers using simultaneous entropy generation analysis and multi-objective genetic algorithm. The European Physical Journal Plus, 2021. 136(10): p. 1019.
[7] Yadegari, M. and A. Bak Khoshnevis, A numerical study over the effect of curvature and adverse pressure gradient on development of flow inside gas transmission pipelines. Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2020. 42: p. 1-15.
[8] Haghighatjoo, H., M. Yadegari, and A. Bak Khoshnevis, Optimization of single-obstacle location and distance between square obstacles in a curved channel. The European Physical Journal Plus, 2022. 137(9): p. 1042.
[9]    Goldsmith EL, Seddon J. Practical intake aerodynamic design. (No Title). 1993 Nov.
[10] Sepahi-Younsi, J., Forouzi Feshalami, B., Maadi, S.R. and Soltani, M.R., 2019. Boundary layer suction for high-speed air intakes: A review. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 233(9), pp.3459-3481.
[11] Akbarzadeh M, Kermani MJ. Numerical Computation of Supersonic-Subsonic Ramjet Inlets; a Design Procedure. In15th. Annual (International) Conference on Mechanical Engineering-ISME2007 May 2007 (pp. 15-17).
[12] Gokhale SS, Kumar VR. Numerical computations of supersonic inlet flow. International journal for numerical methods in fluids. 2001 Jul 15;36(5):597-617.
[13] Duncan B, Thomas S. Computational analysis of ramjet engine inlet interaction. In28th Joint Propulsion Conference and Exhibit 1992 Jul 1 (p. 3102).
[14] Salmi RJ, Stitt LE. Performance of a mach 3.0 external-internal-compression axisymmetric inlet at mach numbers from 2.0 to 3.5. 1960 Jan 1.
[15] Syberg J, Paynter G, Carlin C. Inlet design technology development-Supersonic cruise research. In17th Joint Propulsion Conference 1981 Jul 1 (p. 1598).
[16] Howlett D, Hunter L. A study of a supersonic axisymmetric spiked inlet at angle of attackusing the Navier-Stokes equations. In24th Aerospace Sciences Meeting 1986 (p. 308).
[17] Rodriguez D. Multidisciplinary optimization of a supersonic inlet using a Cartesian CFD method. In10th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference 2004 (p. 4492).
[18] Zuo F, Huang G, Xia C. Investigation of internal-waverider-inlet flow pattern integrated with variable-geometry for TBCC. Aerospace Science and Technology. 2016 Dec 1; 59:69-77.
[19] Sorensen NE, Latham EA, Smeltzer DB. Variable geometry for supersonic mixed-compression inlets. Journal of Aircraft. 1976 Apr;13(4):309-12.
[20] Seddon J, Goldsmith EL, editors. Practical intake aerodynamic design. American Institute of Aeronautics and Astronautics; 1993.
[21] Lu PJ, Jain LT. Numerical investigation of inlet buzz flow. Journal of Propulsion and Power. 1998 Jan;14(1):90-100.
[22] Goldsmith EL, Griggs CF. The estimation of shock pressure recovery and external drag of conical centre-body intakes at supersonic speeds.
[23] Ran H, Mavris D. Preliminary design of a 2D supersonic inlet to maximize total pressure recovery. InAIAA 5th ATIO and16th Lighter-Than-Air Sys Tech. and Balloon Systems Conferences 2005 Sep 26 (p. 7357).
[24] Fujii, M., Ogura, S., Sato, T., Taguchi, H., Hashimoto, A. and Takahashi, T., 2022. Effect of angle of attack on the performance of the supersonic intake for High Mach Integrated Control Experiment (HIMICO). Aerospace Science and Technology, 127, p.107687.
[25] Koval, S., 2021. Analysis of Supersonic Axisymmetric Air Intake in Off-Design Mode. In Proceedings of the International Conference on Aerospace System Science and Engineering 2020 (pp. 43-53). Springer Singapore.
[26] Khobragade, N., Unnikrishnan, S. and Kumar, R., 2022. Flow instabilities and impact of ramp–isolator junction on shock–boundary-layer interactions in a supersonic intake. Journal of Fluid Mechanics, 953, p.A30.
[27] Haines AB. Intake Aerodynamics—Second edition. J. Seddon and EL Goldsmith. Blackwell Science, Osney Mead, Oxford OX2 0EL, UK. 1999. 1407pp. Illustrated.£ 59.50. ISBN 0-632-04963-4. The Aeronautical Journal. 2000 Feb;104(1032):96-.
[28] Moghimi Esfandabadi, M. H., Djavareshkian, M. H. (2023). 'Design and optimization of the             wing fence of a lambda-shaped aircraft model to reduce the rolling moment coefficient', Technology in Aerospace Engineering, (), pp. 13-24. doi: 10.30699/jtae.2023.8.2.2
[29] Lakzian, E., Yazdani, S., Mobini, R., Abadi, M.H.M.E., Ramezani, A., Yahyazadeh, M. and Rashedi Tabar, M., 2022. Investigation of the effect of water droplet injection on condensation flow of different nozzles geometry. The European Physical Journal Plus, 137(5), p.613.