High-Efficiency Combustion Mode in Three-Strut Scramjet Combustor via Clustering Analysis

Abstract This study investigates the influence of five design parameters on the combustion characteristics of a three-strut combustion chamber through single-factor analysis, clarifying their relationship with combustion efficiency and resistance. A Halton sequence with mean squared error–based infill sampling was employed to generate a sample set, and an accurate surrogate model was developed using Gaussian process regression. The Nondominated Sorting Genetic Algorithm II (NSGA-II) was then applied to optimize the chamber geometry with the objectives of improving combustion efficiency and reducing resistance. Through clustering analysis, two distinct high-efficiency combustion modes were identified: a multizone violent combustion mode and a blended mild combustion mode. In the former, the rapid combustion of pilot fuel creates favorable conditions for subsequent fuel combustion, increasing the combustion efficiency from 73% to 93% compared with the baseline case; however, due to excessively abrupt flow field changes, the reduction in resistance is not significant. In the latter, the flame fronts merge and develop smoothly, and although it only improves combustion efficiency to 85% compared with the baseline case, it substantially reduces resistance from − 7,762 newtons (N) to − 8303 N . This work provides enhanced design flexibility for high-performance scramjet combustors.