Propagation Mode Analysis on H2–Air Rotating Detonation Waves in a Hollow Combustor
Wei Lin, Yiheng Tong, Zhiyong Lin, Wansheng Nie, Lingyu Su
Abstract
An experimental study on the propagation mode of –air rotating detonation waves (RDWs) under atmospheric backpressure in a hollow combustion chamber was performed. Experiments were conducted by holding the equivalent ratio at and the mass flow rate of , that is, mass flow rate per unit area of . High-frequency pressure results indicated that increasing mass flow rate shifted the detonation propagation mode from a dual-wave mode with quasi-detonation and detonation mutual transition (comprising three submodes: periodically coupling oscillation, random coupling oscillation, and coupling oscillation with variable wave number) to a single-wave mode with strong instability and finally to a stable single-wave mode. The predetonator was found to play an important role in the stability of detonation propagation. It could bring about injection instability that interacts with the RDWs. Therefore, this interaction, as well as the detonation strength, affects the propagation mode of RDWs. If the predetonator resonated longitudinally, it largely impacts the RDW propagation mode. In the single-wave mode with a lower (e.g., ), the injection instability may cause the propagation frequency to increase, but from the long-term trend, the detonation propagation stability is enhanced with an increase of .