Numerical investigation on self-ignition of PMMA in solid fuel scramjet

The self-ignition performance of polymethylmethacrylate(PMMA) in solid fuel scramjet has been simulated numerically. Regression rate was obtained in steady state by means of solving one-dimensional heat conduction equation coupling the burning surface and the inner flow field, which was based on finite rate and eddy dissipation combustion model of pyrolysis gas. The simulation results were better consistent with the measured data. The effects of inflow air mass flux, total temperature and the configuration of chamber on self-ignition were studied. The results show that the internal flow field in the self-ignition chamber is significantly different with a chamber in which the ingition is not achieved. The PMMA has lean oxygen limit, rich oxygen limit and total temperature limit of self-ignition. Increasing the inflow total temperature contributes to broadening the scope of lean and rich oxygen limit. Self-ignition of PMMA in chamber can not be achieved with either rather short cavity or with a rather shallow cavity. A long and deep cavity is able to achieve self-ignition. The self-ignition is hard to be established with a large diameter of cylindrical section.