Large eddy simulation of combustion characteristics in a kerosene fueled rocket-based combined-cycle engine combustor

• Published in: Acta astronautica 2016-10, Vol.127, p.326-334
• Main Authors: Huang, Zhi-wei, He, Guo-qiang, Qin, Fei, Cao, Dong-gang, Wei, Xiang-geng, Shi, Lei
• Format: Article
• Language: English
• Subjects: Combustion; Combustion characteristic; Compressibility; Flame stabilization mechanism; Flame structure; Kerosene; Large eddy simulation; Navier-Stokes equations; Rocket-based combined-cycle; Rocket-based combined-cycle engines; Stabilization; Turbulent flames
• ISSN: 0094-5765; 1879-2030
• DOI: 10.1016/j.actaastro.2016.06.016

This study reports combustion characteristics of a rocket-based combined-cycle engine combustor operating at ramjet mode numerically. Compressible large eddy simulation with liquid kerosene sprayed and vaporized is used to study the intrinsic unsteadiness of combustion in such a propulsion system. Results for the pressure oscillation amplitude and frequency in the combustor as well as the wall pressure distribution along the flow-path, are validated using experimental data, and they show acceptable agreement. Coupled with reduced chemical kinetics of kerosene, results are compared with the simultaneously obtained Reynolds–Averaged Navier–Stokes results, and show significant differences. A flow field analysis is also carried out for further study of the turbulent flame structures. Mixture fraction is used to determine the most probable flame location in the combustor at stoichiometric condition. Spatial distributions of the Takeno flame index, scalar dissipation rate, and heat release rate reveal that different combustion modes, such as premixed and non-premixed modes, coexisted at different sections of the combustor. The RBCC combustor is divided into different regions characterized by their non-uniform features. Flame stabilization mechanism, i.e., flame propagation or fuel auto-ignition, and their relative importance, is also determined at different regions in the combustor. •An experimental RBCC model configuration is calculated by LES.•Combustion oscillation features and wall pressures are well predicted by LES.•Unsteady combustion characteristics are highlighted by comparison with RANS.•Combustion modes and flame stabilization mechanisms are distinguished.