Interactions of steep-fronted pressure waves with a heterogeneous combustion field

Abstract

Prcssore-fime-position relations and the simuiitaneous determination of other important combustion parameters have been theoretically and experimentally performed. These results were generated along a rocket combnsior axis during propagation of a strong shock wave running back and forth through an heterogeneous combustion field and reflecting ai the combustor ends. The initial steady*state condition is recognized as being that of a Siquid bipropeiilant droplet spray combustion within the burner, limited by their simultaneous vaporization. Substantial interaction effects between the different axial distributions of mass, impulse, and energy sources, affecting the local energy release and the onset and behavior of a sawtooth-like pressure wave have been investigated. In order to study the pressure-time behavior at different burner locations a short shock tube was mounted in the opposite direction to the combustion gas flow at the downstream end of the combustor. This pulse generator functions as an additional external source of pulse energy to initiate the upstreamrunning shock. Therefore a single steep-fronted pressure pulse could enter the combustor axialiy at any time during the run. The governing unsteady differential equations of the gaseous phase have been solved by applying the numerical Lax-Wendroff two-step procedure, including the simultaneous bipropellant vaporization and the wave reflection at the injector end of the combustor. The initial conditions, as given by solving the steady-state problem at first, were filled to corresponding measurements of the local combustion efficiency. This paper compares some of the recently achieved theoretical results with the corresponding experiments.