Effect of the number of cavity flame-holders on combustion efficiency and pressure recovery factor in a supersonic combustion chamber

In the present research work, computational simulation of the multi cavity scramjet combustor has been performed by using the two-dimensional compressible Reynolds-Averaged Navier Stokes (RANS) equations coupled with two equations standard k-ɛ turbulence model as well as PaSR model for combustion modeling. In this combustion chamber, the supersonic air with Mach number of 2.05 flows in the enclosure, and the transverse hydrogen fuel injection is employed at sonic condition. The cavity is used to stabilize the flame in the combustor and the effect of cavity location and also the number of cavities on flow structure, combustion efficiency, and pressure recovery factor are studied. The results show that by increasing the number of cavities from one to four, the combustion efficiency is increased but the pressure recovery factor decreases. For the four-cavity configuration, the combustion efficiency is around 98% and the pressure recovery factor is 46.13%, which shows 26% increase in the combustion efficiency and 10% decrease in the pressure recovery factor as compared with the single-cavity. In the considered configurations, the best performance is achieved by the parallel dual-cavity with two-injection combustor.