High-speed schlieren and particle image velocimetry of the exhaust flow of a pulse detonation combustor

The exhaust flow of a pulse detonation combustor (PDC) is investigated for different operating conditions. The PDC consists of two units: The deflagration to detonation transition section, and the exhaust tube with a straight nozzle. High-speed high-resolution schlieren images visualize the shock dynamics downstream of the nozzle. The flow dynamics during one full PDC cycle is examined via high-speed particle image velocimetry. A well-suited solid tracer particle for supersonic reactive flow is determined in a preliminary study to minimize the PIV measurement error. The investigated operating conditions of the PDC differ in fill fraction, which is the percentage of the tube filled with a reactive mixture. With increasing fill fraction, the flow features grow in size and strength as the propagation velocity of the leading shock increases. The blowdown process of the PDC is characterized by several exhaust and suction phases. An increase in the fill fraction results in a stronger first exhaust phase, whereas the subsequent suction and exhaust phases remain almost unaffected.