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Numerical simulation of the DLR combustor considering the thermochemical non-equilibrium effect

Published online by Cambridge University Press:  01 October 2025

D.E. Chen Open the ORCID record for D.E. Chen [Opens in a new window] ,
Y. Liang ,
S. Zhao ,
C.F. Yue  and
J.B. Wang Open the ORCID record for J.B. Wang [Opens in a new window]
D.E. Chen
Affiliation:
College of Chemical Engineering, Sichuan University, Chengdu, P. R. China Engineering Research Center of Combustion and Cooling for Aerospace Power, Ministry of Education, Sichuan University, Chengdu, P. R. China
Y. Liang
Affiliation:
TaiHang Laboratory, Chengdu, P. R. China
S. Zhao
Affiliation:
TaiHang Laboratory, Chengdu, P. R. China
C.F. Yue
Affiliation:
College of Chemical Engineering, Sichuan University, Chengdu, P. R. China Engineering Research Center of Combustion and Cooling for Aerospace Power, Ministry of Education, Sichuan University, Chengdu, P. R. China
J.B. Wang*
Affiliation:
College of Chemical Engineering, Sichuan University, Chengdu, P. R. China Engineering Research Center of Combustion and Cooling for Aerospace Power, Ministry of Education, Sichuan University, Chengdu, P. R. China
*
Corresponding author: J.B. Wang; Email: wangjingbo@scu.edu.cn
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Abstract

The present work investigates the thermochemical non-equilibrium effect in the DLR combustor using a two-temperature model combined with vibration-chemistry coupling model. Two operating conditions with inflow Mach 2 and 6 are selected for study. The simulation results illustrate that translational-vibrational non-equilibrium is related to energy transfer behaviour and the translational-vibrational relaxation time. When kinetic energy and chemical energy are converted into internal energy, there is a significant difference in the degree of conversion to translational and vibrational energy. If the translational-vibrational relaxation time is larger than the flow time, such as the relaxation time of the mainstream aftershock wave is 0.25 s for the condition with inflow Mach 2, and the flow time is 3 × 10−5 s, non-equilibrium will occur. Significant differences exist between the flow fields with Mach 2 and 6. A clear boundary layer separation occurs at Mach 6. Combustion occurs at the shear layer, which is in translational-vibrational equilibrium, and there are varying degrees of non-equilibrium in other locations. The dissociation of N2 and production of NO primarily occur on the strut walls and the upper/lower walls of the combustor. The mass fraction of NO is higher than the value at Mach 2. The combustion performance is influenced by the thermochemical non-equilibrium effect. At the condition of Mach 2, it increases the combustion efficiency by 10% near the injector and 0.27% at outlet relatively. Non-equilibrium inhibits the initial upstream combustion while slightly promoting downstream combustion under inflow Mach 6 condition.

Keywords

translational-vibrational non-equilibriumvibration-chemistry couplingDLR scramjet combustornumerical simulation

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Type
Research Article
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The Aeronautical Journal , First View , pp. 1 - 22
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© The Author(s), 2025. Published by Cambridge University Press on behalf of Royal Aeronautical Society

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