Effects of blockage ratio on the propagation characteristics of hydrogen-rich gas rotating detonation

The propagation characteristics of a hydrogen-rich gas/air rotating detonation wave (RDW) were investigated for different blockage ratios (BRs). Two rotating detonation chamber (RDC) widths were used in combination with different RDC exit widths to obtain different RDC BRs. The variations in the RDW propagation modes and wave velocities at different BRs and equivalence ratios (ERs) were studied and analyzed. The experimental results show that four types of RDW propagation modes can be obtained (single wave, single wave/counter-double waves hybrid mode, triple waves, and unstable triple waves) by changing the BRs and ERs. For BR > 0.64, the RDW exhibits a triple waves mode. The RDC width also affects the RDW propagation mode. The results show that at low BRs, the change in the RDW propagation mode owing to the injection pressure difference is the main influence mechanism. As the BR increases, the influence of the reflected shock wave from the exit of the RDC increases, which plays an important role in the generation of the triple waves mode. The stability of RDW propagation can be improved by appropriately increasing the blockage ratio in the RDC. The 26 mm RDC width at BR = 0 results in a maximum wave velocity of 1933.8 m/s. Moreover, the stability of the RDW propagation is poor at low and high BRs.