Effect of compression ratio on performance of solid fuel scramjet

The effect of compression ratio on performance of solid fuel scramjet at a flight Mach number of 6 and an altitude of 25 km has been investigated theoretically and numerically. Multispecies Navier-Stokes equations and shear stress transport k-ω model are solved numerically. The polymethyl methacrylate(PMMA) solid fuel and a global one-step reaction mechanism are used to simulate the combustion. The results indicate the thrust and specific impulse decrease with the internal contraction ratio increases. The increase of exit/inlet area ratio in the cavity region has a large influence on mass and heat addition. In the condition of the same area ratio, the engine performance is improved significantly as internal contraction ratio increases, while the engine performance is improved a little with the increase of external turning angle. The increase rate of thrust and specific impulse become small gradually due to great total pressure losses. There exists optimal level compression for solid fuel scramjet which is affected by constraint of inlet starting.