Numerical Study of Mixing Enhancement by Shock Waves in Model Scramjet Engine

Abstract

Anumerical study hasbeenconductedto investigatetheeffectofshockwaveson thesupersonichydrogen ‐airjet e ame stabilized in a Mach 2.5 circularcross-section combustor. Thenumerical model utilizes multispecies Navier ‐ Stokes equationswith detailed chemical reaction modelsand employsa k‐! shear stresstransport model. A wedge is mounted on the side wall of the combustor in order to e nd the interaction of the oblique shock waves with the hydrogen‐air jetlike e ame. The interaction between the shock waves and the mixing layer is classie ed according to the increasing tendency of the growth rate of the mixing layer downstream of the shock waves. It is found that the shock wavescreatea radially inward/outward aire owto thee ame and elongatea e ame-holding recirculation zone, and thus fuel ‐air mixing is enhanced signie cantly, resulting in improved combustion efe ciency. Also, the overall performance is investigated by changing the shock position and considering the mixing/combustion efe ciency and total pressure loss in a model scramjet combustor. Because there exists a tradeoff between the enhanced mixing/combustion efe ciency and the decreased total pressure recovery, it is suggested that the optimized shock position needs to be determined in order to obtain the maximum overall combustor performance using the overall performance index.