Measurement of Pressure-Rise in a Pulse Detonation Engine

Abstract

*† ‡ § Experimental measurements of static pressure -rise and thrust are made in a pulse deton ation engine (PDE). The research employs a valved ethylene -air 3 -tube PDE at an operating frequency of 20 Hz per tube. New terminology and definitions for pressure -rise in a PDE are introduced. The mean PDE fired static pressure was quantified with both low and high frequency pressure sensors. Pressure measurements were obtained at the combustor head -end and tail -end for configurations with straight and converging exit nozzles. It was determined that the high frequency pressure measurements provided a more accurate measure of the mean PDE fired pressure. The test measurements are used to validate computational predictions obtained using a quasi -1D limit cycle code. The overall PDE pressure -rise was found to be sensitive to system flow losses and the e xit nozzle geometry. It was observed that in an un -optimized configuration, with straight exit nozzle, the PDE operated with an overall pressure loss instead of a pressure gain. However, an overall pressure gain was observed when the PDE included a conve rging exit nozzle. The PDE thrust was quantified using a thrust stand to measure thrust directly, and by using tube pressure measurements to calculate thrust. The thrust calculated by pressure measurements was found to over -predict both the thrust stand measured thrust and computational thrust predictions.