Numerical Investigation on Flame Stabilization of Cavity-Based Scramjet Combustor Using Compressible Modified FGM Model

Qi Zhang,Hong Chen,Weibing Zhu,Dongchao Yang,Valeria Di Sarli

doi:10.1155/2022/8388827

Qi Zhang, Hong Chen + Show 3 more

Open Access

https://doi.org/10.1155/2022/8388827

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Abstract

The technology of flame stabilization on cavity-based scramjet combustor has great significance in the field of future spacecraft. In this paper, a compressible modified FGM model was established based on the idea of the flamelet model, which was adopted to simulate the unsteady combustion process of the hydrogen transverse jet in the upper cavity of the scramjet. The results show that the compressible modified FGM model can accurately reflect the flow field and the propagation process of the flame in the supersonic cavity, and can capture the fine shock structure in the flow field. The coupling effect of shock waves and shear layer cause the shear layer to quickly destabilize, resulting in the turbulence effect, which promotes the mixing of air and fuel. The boundary layer separation at the upper wall of the combustion chamber will reduce the stability of the shear layer.

Highlights

Hypersonic vehicle usually refers to a flight power device with a flight speed of more than Mach 5 [1, 2]
A compressible modified FGM model suitable for supersonic combustion is established by improving the method of solving compressible flow field parameters. e integrity and stability of the model are verified by simulating the combustion flow field of a typical DLR scramjet combustion chamber
A hybrid RANS/LES turbulence model coupled with k-ω SST model proposed by Gritskevich is used to solve the turbulent flow field [60]. e combustion model adopts nonpremixed compressible modified FGM model. e reaction mechanism between hydrogen and air is based on the 19-step reaction mechanism of 9 species (H2, O2, N2, H2O, OH, H, O, HO2, H2O2) given by Jachimowski [57], as shown in Table 3. e viscosity of each species of the gas is given according to equation (6), and the specific heat is determined according to the JANAF physical properties table

Summary

Introduction

Hypersonic vehicle usually refers to a flight power device with a flight speed of more than Mach 5 [1, 2]. E results show that the FGM model can effectively improve the computational efficiency and realize the accurate simulation of the flame form. A compressible modified FGM model suitable for supersonic combustion is established by improving the method of solving compressible flow field parameters. Combining with hybrid RANS/LES turbulence model, the unsteady combustion process of hydrogen transverse jet in a cavity-based scramjet is numerically simulated. Compared with the experimental results of Fan et al, it is found that the simulation can accurately capture the formation of flame, distribution of shock waves, and the phenomenon of “flame lifting” in a single cavity combustion chamber. The combustion stabilization mechanism of the cavity structure is analyzed by combining the phenomenon of shock waves and boundary layer, which provides a reliable theoretical basis for the design of the scramjet engine

Numerical Approach

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Numerical Simulation Results

Analyses and Discussions

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Conclusions