Investigation of the Exhaust Flow of a Pulse Detonation Combustor at different Operating Conditions based on High-Speed Schlieren and PIV

TL;DR

This study uses high-speed schlieren and PIV to analyze how different fill-fractions affect shock dynamics and flow features in a pulse detonation combustor's exhaust at various operating conditions.

Contribution

It introduces a novel PIV measurement approach with optimized tracer particles to accurately capture flow dynamics in a PDC's exhaust.

Findings

Flow features grow in size and strength with higher fill-fraction.

Leading shock propagation velocity increases with fill-fraction.

The first exhaust phase becomes stronger as fill-fraction increases.

Abstract

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 blow down process of the PDC is characterized by several exhaust and suction phases. An increase in fill-fraction results in a stronger first exhaust phase, while the subsequent suction and exhaust phases remain almost unaffected.