Results of both experimental and three-dimensional numerical studies on H 2 /air continuous rotating detonation are presented. Tangentially injected H 2 /O 2 hotshot jet was used to ignite the engine successfully. Under the condition of air and hydrogen mass flow rates of 265 and 7.7 g/s and the ambient pressure of 11 kPa, H 2 /air continuous rotating detonation has been realized for about 300 ms. Time-frequency characteristics of the measured results were analyzed by different methods, and the results agreed well with each other. The detonation wave propagated stably during the test, with the propagation frequency variation of 5.35-5.85 kHz. The mean propagation velocity was 1674.3 m/s, which was about 85.0% of the theoretical value. Corresponding three-dimensional numerical simulation was carried out. Flow field structure of the rotating detonation wave was analyzed, and the curvature effect was also considered. Propagation processes of both the experiment and simulation results were compared. The variation of detonation wave propagation frequency of the simulation case was 6.262-6.27 kHz, with the mean propagation velocity of 1870.1 m/s, which was larger than the experiment result. Distribution of the mean combustor pressure along the axis direction was analyzed. Within the heat release zone, the mean pressure decreased greatly, and it changed gently beyond this zone. The changing tendency of both the experimental and numerical results agreed with each other, but there were differences between the pressure values.
A new method to initiate and sustain the detonation in supersonic flow is investigated. The reaction activity of coming flow may influence the result of detonation initiation. When a hot jet initiates a detonation wave successfully, there may exist two types of detonations. If the detonation velocity is greater than the velocity of coming flow, there will be a normal detonation here. Because of the influence of boundary layer separation, the upstream detonation velocity is much greater than the Chapman—Jouguet (CJ) detonation velocity. On the other hand, if the detonation velocity is less than the velocity of coming flow, an oblique detonation wave (ODW) will form. The ODW needs a continuous hot jet to sustain itself. If the jet pressure is lower than a certain value, the ODW will decouple. In contrast, the normal detonation wave can sustain itself without the hot jet.
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