Interplay of self-throttling and air throttling on combustion enhancement of the scramjet combustor

Abstract

The present work discusses the effects of self-throttling in conjunction with air throttling on the scramjet combustor performance. Ethylene fueled cavity-strut based combustor is considered and LES simulations are performed to gain insight on influence of Mach number, inlet temperature, self-throttling and air throttling on combustion performance. Our study shows substantial improvement both in mixing and combustion efficiency of the combustor. This is evident from the flow characteristics like shock, vortices, recirculation zones, mixing length and penetration depth. It is found that pressure profile is distributed more uniformly across the combustor with minimum pressure losses. Complete mixing is attained relatively earlier as a result of intense shock-shear interactions. Furthermore, the enhancement in the combustion performance is greater at higher Mach number. The increase in static pressure is found to be a strong function of the inlet Mach number and temperature also. The separate study on effect of initial temperature indicates the mixing length is the shortest with the maximum fuel penetration at inlet temperature of 700 K beyond which the performance deteriorates. It is seen that air throttling is found to be more effective when self-throttling works in tandem alongside having a direct bearing on the combustor performance.