ISSN Online: 2379-1748
ISBN Flash Drive: 978-1-56700-431-1
ISBN Online: 978-1-56700-430-4
First Thermal and Fluids Engineering Summer Conference
ACTIVATION OF DETONATION-TO-DEFLAGRATION TRANSITIONS IN PULSED DEONATION COMBUSTOR BY WALL HEATING
Abstract
A series of experiments were performed with a liquid fuel pulsed detonation combustor that is a 20-mm dia partitioned tube equipped with a pre-chamber shaped as a hemispherical cavity with a conical duct for transition to the tube. The total length of the setup is 664 mm. A mixture is being ignited by a spark plug mounted in the closed endwall of the combustor. Fuel is being injected by the injector located in the intersection zone of hemispherical and conical parts of the pre-chamber. Analysis of large-number of working cycles with combustion of near-stoichiometric heptane/air/oxygen mixtures (φ = 1.04) revealed a variation of the wave velocity in the range 500 − 2500 m/s. The detonation was recorded at distances 140 − 640 mm from place of spark that is 7 − 32 tube diameters. It was shown that such scatter of the wave velocities and pre-detonation distances was due to a degree of thermal activation of a mixture prior to its ignition.