Rapid and efficient fuel-air mixing plays an important role in the successful operation of supersonic combustion ramjets (scramjets). In order to evaluate the mixing performance of the pulsation injection scheme, this paper presents the 2-D and 3-D numerical investigation of the hydrogen fueled HyShot II scramjet with pulsed fuel injections. This work focuses on the cold flowfield characteristics and fuel-air mixing performance only. Reynolds-Averaged Navier-Stokes equations were solved by using the ANSVS FLUENT v!7.1. Good agreements between the numerical results and experimental data can be obtained by using the two equation k-w SST turbulence model. Pulsed fuel injection is added by employing total pressure pulses. The total pressure peak is maintained as the same with the one that chokes the fuel injector in steady operations. Different frequencies (0 kHz, 5 kHz, 10 kHz, and 20 kHz) of pulsed injections are investigated. It is found that the fuel streams in pulsed fuel injections have wavy patterns, and the shock structures show unsteadiness under the effects pulsation injection. Among the tested high frequency injections, the fuel penetration depth decreases when the pulsed frequency increases, but the mixing efficiency is found to be improved although it also depends on the frequency significantly.
展开▼
