Characterization of Pulse Detonation Engine Performance with Varying Free Stream Stagnation Pressure Levels

摘要

A pulse detonation engine operates on the principle that a fuel-air mixture injected into a tube will ignite and undergo a transition from a deflagration to a detonation and exit the tube at supersonic velocities. Studies in the field of combustion have shown that both ignition time and deflagration to detonation transition time can vary as a function of pressure. It can be hypothesized that if ignition and deflagration to detonation transition times can be reduced by increasing the free stream stagnation pressure level of the tube, it would then be possible to shorten the detonation tube length and increase the cycle frequency resulting in a weight savings, and an increase in overall pulse detonation engine performance. By attaching varying sizes of nozzle orifices to the exhaust exit of the pulse detonation tube of the pulse detonation engine to choke, or increase the stagnation pressure levels of the detonation tube it was shown possible to vary the internal pressure of the pulse detonation tube and examine the effect on the performance parameters of ignition time, and detonation wave speed, distance, and time. By varying fill fraction, spark delay and equivalence ratio in addition to nozzle orifice size, a reduction in ignition and overall detonation time was achieved from a variation of nozzle orifice to detonation tube diameter ratios. The effects of pressure in this study produced a less beneficial effect on deflagration to detonation transition time and distance.