Branched Detonation in a Multi-Tube PDE
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH
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The Air Force is conducting research on the use of a Pulse Detonation Engine PDE for a wide variety of applications. The PDE derives thrust through the development of a combustion-induced detonation wave in a tube. One research objective is to increase the firing frequency in multiple tubes by reducing the ignition and detonation initiation time. Increasing the firing frequency will produce an increase in thrust. In the baseline configuration, ignition of a stoichiometric hydrogen air mixture in a PDE tube occurs from a spark plug. A more powerful ignition method exploits the detonation energy from an adjacent thrust tube to rapidly ignite the fuel-air mixture. Rolling et al., were able to branch a detonation wave from one tube to another through a crossover tube, ignite the fuel-air mixture in the second tube, and transition to a detonation using a deflagration to detonation transition DDT device. In the current work, the detonation arrival location has been moved to the head, and the overall benefits of reduced ignition and DDT times are quantified. Results show that the time required to ignite, DDT, and exit a detonation wave was reduced by 45.5 to 63.1 by using a branched detonation. Additionally, the time from ignition to full tube blow down was reduced by 16.6. These reductions in time equate to an appreciable increase in the allowable firing frequency. Instances of detonation initiation were also achieved in the second tube without a DDT device.
- Combustion and Ignition
- Jet and Gas Turbine Engines