Numerical and experimental investigation of an adjustable dual-channel supersonic diffuser

The conventional diffuser performance is constrained by the optimal contraction ratio and the start-up contraction ratio. In order to balance the start-up performance and operating performance, the diffuser can be designed to be adjustable. Existing adjustable diffuser configurations have different drawbacks and most of them lack experimental verification. Therefore, a new parallel dual-channel diffuser scheme is proposed. The diffuser operates at Ma 4 and uses simple transmission devices to achieve an adjustment in the contraction ratio. The performances of the dual-channel mode, single-channel mode and the mode conversion are tested experimentally. The diffuser exhibits good starting and anti-backpressure capabilities. The unsteady numerical results show that the increase in the anti-backpressure capability of the diffuser is mainly due to the increase in the number of oblique shock waves in the main channel and the backward movement of the leading shock.