Pulse Detonation Engines (PDE) operating on liquid hydrocarbon fuels are limited to operating frequencies of 35 Hz due to long ignition times from a low energy ignition sources. This study shows ignition time of JP-8 can be nearly eliminated by igniting a thrust tube using a secondary detonation. A counter flow heat exchanger attached to a thrust tube utilized waste heat from the detonation process to heat JP-8 to supercritical conditions. The fuel flash vaporized when injected into the air stream of the engine. A detonation was produced by a spark in a 5 cm diameter, 1.37 m long tube. The detonation was then propagated in a 1.9 cm diameter crossover tube into the head of second thrust tube where a pressure transducer and hydroxyl (OH) sensor measured the combustion event. Branch detonation was performed over a range of equivalence ratios ranging from 1.05 to 1.3. Branch ignited thrust tubes have shown 40% improvement in deflagration to detonation transition (DDT) time and a slight improvement in DDT distance.
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