Numerical investigation on combustion performance optimization with strut/wall combined-staged injection strategy within an axisymmetric variable geometry combustor at Mach 3

Numerical simulations were conducted on the strut/wall multistage injection strategy to optimize the combustion performance at Mach 3. Two kinds of the combustion models were used: The Eddy-Dissipation Model (EDM) was used first to highlight the effects of mixing performance on the combustion performance; then the Finite-Rate/Eddy-Dissipation Model (FR/EDM) was used to modify the influence mechanism of wall injection positions by incorporating with finite-rate reaction effects. The combustion process was divided into three stages to analyze the average heat release rate and the contribution of average total temperature change of each stage to identify the key influencing factor of each stage. The results indicated that under low flight Mach number conditions, the finite-rate reaction effects exerted a more pronounced influence on the combustion. The strut/wall multistage injection strategy was found to be an effective means of enhancing combustion, with the positive feedback between the strut flame and the wall flame being particularly influential. Additionally, apart from the mixing efficiency, the distribution of heat release length of each stage also emerged as a critical factor in determining combustion performance. By adjusting the wall injection positions, the better combustion performance and the bigger working stability of the combustor could be achieved. The study elucidated the regulatory strategy of wall injection positions on combustion performance, offering value insights for optimizing combustion performance under low Mach number conditions.