A New Ignition System for Pulse Detonation Engine

Abstract

A new ignition system is applied to pulse detonation engine (PDE), which is flame jet ignition (FJI) system, to enhance a deflagration to detonation transition (DDT) time and length. The idea of FJI is not new, but its use to PDE has not been seen ever. The present study is to show the feasibility of FJI to PDE by comparing with a conventional spark ignition (CSI) system. FJI system has a small sub-chamber of 0.5-12.8 cm 3 in volume with a spark plug to produce a lot of ions and radicals in the PDE main chamber. Three subjects are studied: 1) to optimize the best configuration of FJI sub-chamber to obtain its basic design, 2) to evaluate FJI performance on multi-cycle operation using the best FJI configuration, 3) to visualize the ignition mechanism by FJI system in the PDE chamber. All experiments are also compared with those operated by the CSI system. As for results, the best size and design for FJI system is obtained using a non-dimensional value. The FJI system is shown to be a most effective ignition system to shorten DDT time by a factor of 3.9 comparing with the CSI system. A visualization of injection system by Schlieren movies reveals the essence of faster flame ignition and propagation by FJI system.