Pressure rising slope variation accompanying with combustion mode transition in a dual-mode combustor

Abstract

Direct-connect experiment with equivalence ratio linear increasing in a dual-mode combustor with a strut is conducted at free stream Mach number of 2.0. Based on the pressure histories on side wall, pressure rising slope variation accompanying with combustion mode transition is found and discussed. The pressure rising has different slopes vary as equivalence ratio linearly increasing. Meanwhile, this characteristic of pressure slope variation leads to the change of combustor thrust. By analyzing the combustion heat release zone and the geometric configuration combustor, a typical simplified geometric model is proposed and studied by using numerical simulation. The phenomenon of the pressure rising slope variation is obtained and explained by the shock train movement in numerical simulation. In the process of shock train movement, a normal shock is established at thermal throat to make the airflow of throat position reach critical state, which could limit the mass flow rate of the supersonic mainstream. Further, inviscid and isentropic flow analysis is employed to illustrate the variation of pressure rising resulted from the occurrence of a normal shock wave. The analysis indicates that the cross-sectional area of mainstream is bounded by the subsonic boundary layer plays a key role to alter the pressure rising slope.