Numerical investigation of the unsteady flow and wave dynamics in a wave rotor combustor

Abstract

The pressure gain combustion in wave rotors has the potential to significantly enhance the performance of gas turbine engines. Wave rotor design focuses on understanding the complex behavior of rotating channels, which is challenging due to high rotational speeds. To investigate the influence of different working conditions on the unsteady process within the wave rotor combustor, a simplified 24-channel model was established to study both the unsteady flow and the wave dynamics. The calculations indicate that, for the current port position adopted and a rotor speed of 4000 rpm, backflow occurs at the inlet port for various inlet pressures. By analyzing the working sequence of the wave rotor combustor, it is found that the inlet port does not close in time when the pre-compression wave returns. This delay results in reflected expansion waves or compression waves moving within the channel, which affect a portion of the pressure gain, leading to a damped sinusoidal trend in the pressure profiles within the channel. The optimal pre-pressurization effect can be achieved at a rotor speed of 2000 rpm for the test conditions considered, and the total pressure gain achieved was 6.3%. By adding hot-jet ignition, it is found that the shock wave and flame interact at least five times in the current simulation. The shock–flame interaction can greatly accelerate the process of chemical reactions. After the fourth interaction, the shock wave achieved local coupling with the flame, forming a local high-pressure area of 4 bar, verifying the effectiveness of the wave rotor as a constant-volume supercharging device.