Difference of self-ignition performance in solid fuel scramjet with step or cavity

The self-ignition process of poly-methyl-methacrylate and the effect of combustor shape with step or cavity on self-ignition in solid fuel scramjet were simulated numerically. An unsteady, two-dimensional, axisymmetric, turbulent (SST model), reaction (finite-rate/eddy dissipation reaction model), one dimensional heat conduction between the gas and solid fuel grain model was solved numerically. Main conclusions are as follows. Both of step and cavity could establish self-ignition. The self-ignition processes of these two flame-holders are consistent. Self-ignition could be established under a relatively wide range of inlet conditions for cavity compared with step. A cavity with appropriate length enhances not only the self-ignition performance but also the overall performance. Cavity is the advanced flame-holder which can be used for self-ignition in SFSCRJ combustor.