Investigations on multicycle spray detonations

Abstract

Experimental investigations were carried out on a 50-I.D. multicycle pulse detonation engine (PDE) model, and liquid fuel (gasoline) was used. The average of pressure peak, as measured by piezoelectricity pressure transducer, increased versus distance to thrust wall before fully-developed detonation came into being. According to the pressure history, the pressure in detonation tube would not rise abruptly until the flame front advanced a certain distance downstream the spark. Just at that moment, two compression waves spreading to opposite direction were formed. One was enforced by combustion and became detonation rapidly. The other was weakened because of obstacles and insufficiency of fuel. Two methods were used to determine the induction length of two-phase detonation wave through the pressure history. Ignition delay time was found to be longer than deflagration-to-detonation transition (DDT) time, and the sum of the two would change little as cycle frequency increased. So they could be the most important factors controlling two-phase PDE frequency. Filling process and blowdown process were also analyzed.