Detonation Initiation Studies and Performance Results for Pulsed Detonation Engine Applications

Abstract

Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Dayton, OH 45440Abstract An in-house computational and experimental program to investigate and develop an air breathing pulse detonation engine (PDE) that uses a practical fuel (kerosene based, fleet-wide use, "JP" type) is currently underway at the Combustion Sciences Branch of the Turbine Engine Division of the Air Force Research Laboratory (AFRL/PRTS). PDE's have the potential of high thrust, low weight, low cost, high scalability, and wide operating range, but several technological hurdles must be overcome before a practical engine can be designed. This research effort involves investigating such critical issues as: detonation initiation and propagation; valving, timing and control; instrumentation and diagnostics; purging, heat transfer, and repetition rate; noise and multi-tube effects; detonation and deflagration to detonation transition modeling; and performance prediction and analysis. An innovative, four-detonation-tube engine design is currently in test and evaluation. Preliminary data are obtained with premixed hydrogen/air as the fuel/oxidizer to demonstrate proof of concept and verify models. Techniques for initiating detonations in hydrogen/air mixtures are developed without the use of oxygen enriched air. An overview of the AFRL/PRTS PDE development research program and hydrogen/air results are presented.

Experimental study of an air-breathing pulse detonation engine ejector

“…The rise time of the pressure is within the order of 10 À5 s. The pressure spikes of transducer 11 are much smaller than transducer 10's. This indicates that PDE operated in a partially-filled mode [21][22][23]. There was no gasoline/air mixture near the location of transducer 11 when the detonation wave arrived here.…”

Experimental investigation of effect of partial filling on the impulse of pulse detonation engine

“…Eqs. (5) and (6) are suitable for the range of β cr ≤β≤1. In other words, detonable mixture section length must be longer than that of deflagration to detonation transition, otherwise detonation cannot be achieved.…”

“…While the PDE presents a mechanically simple device, its unsteady thermo-fluid dynamics are quite complex. As may be expected with such a relatively new technology, the study on the approaches for achieving optimum design and performance is only at the initial stage and needs further exploration.In the past few years, numerous studies on the effects of partial mixture filling on PDE performance have been reported analytically, numerically and experimentally [5][6][7][8][9][10][11][12] . Zitoun et al [5] measured the single-cycle impulse of ethylene-oxygen mixtures under standard conditions in a detonation tube and an extension with the same cylindrical cross section.…”

“…They directly initiated a detonation with approximately 35 J of energy and the impulse was calculated by integrating the thrust surface pressure differential. Schauer et al [6] studied the effects of the pressure relaxation rate upon thrust experimentally by adjusting the amount of detonable mixture in the tube while maintaining the same detonation tube length. Significant performance gains were observed.…”

Combustion onset in non-uniform dispersed mixtures

“…Thus combustible mixtures formation and deflagration or detonation initiation in poly-dispersed fuel-air mixtures are the key aspects providing different limitations for operation of those engines. Onset of detonation being very dangerous for conventional engines could, however, serve the basis for creating new generation of engines-pulse detonating engines (PDE) [1][2][3]. Dispersed mixtures having been formed by different pulverizers could not be spatially uniform.…”