Testing and Acoustic Transient Simulation of Pulse Excitation in Liquid Rocket Engines

Targeting the dynamic combustion stability assessment of liquid rocket engines, a pulse gun was designed, optimized, and tested for shock performance. The frequency characteristics of pressure responses in high-pressure acoustic chambers under pulse excitation were obtained, while CFD simulations reproduced the transient evolution of pulse excitation. Results indicate that removing the throttle orifice and using short, thick barrel channels reduces pressure rise, enhances oscillation effects, and achieves a maximum overpressure ratio of 97% under 10MPa backpressure. Lower longitudinal fundamental frequencies tend to form multi-order longitudinal oscillation modes. CFD calculations accurately captured the propagation, reflection, and superposition of pressure perturbations. Nonlinearity induced by high amplitudes caused the “compression-rarefaction” phenomenon in the wave system, while large-scale vortex structures flanking the jet core led to rapid velocity decay and potential acoustic energy dissipation.