Experimental investigation on valveless air-breathing dual-tube pulse detonation engines

Two-phase dual-tube air-breathing pulse detonation engine (APDE) experiments were performed to improve the understanding of the characteristics of valveless multi-tube APDE. Two different operation patterns were studied: simultaneously and single-tube firing. The synchronicity of detonation waves was quantified. The time interval was less than 1 ms and decreased with the increasing frequency. It was found which detonation wave arrived firstly had a degree of randomness. The situation that the detonation wave in a certain tube always kept ahead never happened in the experiments. The back-propagation pressure wave in the upstream inlet was also not synchronous. Its synchronicity was a little inferior than the detonation wave's and also improved with the increasing frequency. The pressure-rise occurred twice successively in the common air inlet and prolonged the period of pressure oscillations therein. The results of single-tube firing showed that the flow field in the non-detonate chamber was not only influenced by the diffracted wave downstream from the neighboring tube but also by the upstream-propagating pressure wave. Compared with the dual-tube firing, the operation pattern of single-tube firing is beneficial to reduce the pressure disturbance in the common air inlet.