Study on the Operation of Pulse-Detonation Engine-Driven Ejectors

Abstract

Experimental studies were performed to improve the understanding of the operation of ejector augmenters driven by a pulse-detonation engine. The research employs an H 2 -air pulse-detonation engine at an operating frequency of 30 Hz.Static pressure was measured along the interior surface of the ejector, including the inlet and exhaust sections. Thrust augmentation provided by the ejector was calculated by integration of the static pressure measured along the ejector geometry. The computed thrust augmentation was in good agreement with that obtained from direct thrust measurements. Both straight and diverging ejectors were investigated. The diverging ejector pressure distribution shows that the diverging section acts as a subsonic diffuser and has a tremendous impact on the behavior of the inlet entrainment flow. Static-pressure data were also collected for various ejector axial positions. These data supported the thrust augmentation trends found through direct thrust measurements. Specifically, the optimum axial placement was found to be downstream of the pulse-detonation engine near x/D PDE = +2, whereas upstream placements tend to result in decreasing thrust augmentation. To provide a better explanation of the observed performance trends, shadowgraph images of the detonation wave and trailing vortex interacting with the ejector inlet were obtained.