Turbulence-driven shock wave enhancement in detonation engines through obstacle design across hydrogen, acetylene, and kerosene

Pre-detonators serve as preferred shock initiators in aerospace applications, particularly when prioritizing power and weight over direct initiation with substantial energy demands. Strategically positioned obstacles within pulse detonation engines play a crucial role in shortening shock generation time while ensuring unimpeded blast passage. Enhanced turbulence within the duct contributes significantly to achieving elevated temperature, pressure, and velocity levels, resulting in more robust shock waves, particularly at heightened equivalence ratios. Accordingly, this study delves into the numerical investigation of hydrogen-oxygen, acetylene-oxygen, and kerosene-oxygen couples in two-dimensional configurations. The investigation encompasses obstacle heights ranging from 0.5 to 1.5 mm within tubes, evaluated at equivalence ratios of 0.5, 1.0, and 1.5 under identical initial conditions. The numerical analysis discerns variations in pressure, temperature, and velocity parameters induced by diverse fuels and obstacle ratios from shock wave inception to tube exit. Within our designed Ø10 × 210 mm pre-detonator, acetylene and hydrogen were observed to generate shock waves approximately 20 mm from the tube inlet. Specifically, hydrogen demonstrated the highest velocity among all fuel-oxygen mixtures, registering 1672.64 m/s at a 0.5 mm barrier height and 0.5 equivalence ratio. Acetylene at a 1.5 mm obstacle height and 1.0 equivalence ratio exhibited a peak average flame temperature of 8940 K. For kerosene, escalating obstacle heights at 0.5 and 1.0 equivalence ratios led to amplified temperature, pressure, and velocity values. These findings underscore the importance of tailoring blockage ratio and equivalence ratio levels, especially for highly reactive fuels like hydrogen, to optimize shock wave performance in pre-detonator applications.