Numerical analysis of detonation wave propagation in a closed linear combustor with doublet injectors at low plenum pressure

抄録

In the flow field of a rotating detonation engine (RDE), the detonation wave propagates through the reaction with the continuously injected fuel and oxidant mixture. In the previous research using the actual RDE, due to insufficient mixing, combustor shape, centrifugal force, and so forth, the detonation wave velocity generated in RDE is usually significantly lower than the characteristic Chapman-Jouguet (C-J) velocity for the corresponding mixture. In order to elucidate the effect of incomplete fuel mixing on detonation propagation inside RDE, a closed linear combustor (CLC) with doublet injectors that can change the injection angle was constructed. A lower plenum pressure was examined because supersonic fuel injection shock waves would affect detonation wave propagation. To verify feasibility of the experiment and obtain the predicted value, numerical analysis of detonation wave plunging entry combustible gas jet train of the premixed fuel and non-premixed fuel at three injection angles (perpendicular to the bottom wall, 70 degrees, and 45 degrees) were carried out. The fuel and oxidant use Ethylene (C₂H₄) and Oxygen (O₂) respectively. The results showed that the effects of detonation wave pressure on the injectors arranged along the propagation direction of blast wave are obviously less than that of the jet ports arranged perpendicular to the bottom wall and opposite directions of detonation propagation. Although the detonation propagation velocity of non-premixed fuel is lower than that of premixed fuel, it could also reach more than 90% of the C-J velocity after the promotion of mixing. Compared with pure non-premixed gas, the detonation velocity increases by about 50%. Therefore, the performance is expected to be improved by creating a structure in the RDE that allows the fuel and oxidizer to intersect in advance and be injected in the direction of the detonation wave propagation. The numerical results also confirm that the reflection wave from the top of the CLC does not affect the propagation and visualization of the detonation wave.