Investigation on the Combustion Characteristics of a Reverse-Flow Pulse Detonation Combustor Under Different Fuel Supply Pressure and Fuel Nozzle Diameters

In order to elucidate the impact of fuel supply pressure on nozzle performance, experimental campaigns were designed to analyze the coupled influence of fuel supply pressure and nozzle diameter across engine incoming conditions, thereby elucidating the relationship between atomization particle size and supply pressure. Building upon these findings, the study further investigated the influence of nozzle diameter on the detonation characteristics, operational stability, and pressure gain dynamics of a reverse-flow PDC configuration. The results show that increasing the incoming flow stagnation temperature promotes droplet fragmentation through multiple physical mechanisms, leading to a rapid decline in Sauter Mean Diameter (SMD). Under the most extreme operating condition, the SMD was observed to decrease to 6 μm. Concurrently, an increase in incoming flow stagnation pressure augmented the airflow density and fuel–air relative velocity, further contributing to the reduction in average SMD. The 0.4 mm diameter nozzle exhibited optimal atomization performance across all tested conditions, accompanied by the shortest deflagration-to-detonation transition (DDT) distance, enabling reliable detonation initiation under low-load operational regimes (5 Hz, 0.15 MPa, 323 K). Additionally, improved atomization quality was found to marginally enhance pressure gain ratio. These findings provide critical insights for the engineering realization of pulsed detonation combustor technologies.