On scale effect of supersonic combustion in axisymmetric combustor

Abstract

Due to the different structure and flow mechanism, whether the scale effect law obtained at the rectangular interface can be applied to the axisymmetric combustor remains to be urgent studied. The present paper investigates the time-scale effect of combustion and flame propagation in axisymmetric combustion chamber, analyze the influence of time-scale change on supersonic combustion, and clarify the scale effect of supersonic combustion flame stability, which including experiments, numerical simulations, theoretical modeling, and systematic analysis. In cold flow, the small-scale configuration produces a large separation bubble at the inlet position and the boundary layer thickness is relatively thick. The total pressure loss from the inlet to the injection position is large, but the relatively weak shock wave downstream of the cavity results in the minimum total pressure loss from multiple scale combustors. The heat release in the small combustion chamber is slowly released in the downstream expansion section of the throat, making the air flow always accelerate. Based on the above analysis, the reasons for the strong flame in the large-scale combustion chamber can be summarized as follows: the spatial scale and time scale of the flow increase simultaneously with the increase of the size of the combustion chamber. The size of the combustion chamber has no effect on the combustion time scale. Although the relative thickness of the boundary layer becomes thinner, the absolute subsonic region of the boundary layer filled with combustion increases, which is conducive to the intense occurrence of combustion.