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.

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.

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. Two methods, an ejector pump and a turbo-charger, are evaluated as a means to self-aspirate a Pulsed Detonation Engine (PDE). For the experiments pertaining to the ejector pump, a pulsed detonation engine is run on hydrogen and air at frequencies up to 40 Hz, equivalence ratios from 0.5 to 1.0, and fill fractions from 0.25 to 1.0. Flow visualization is used to determine the combination of fill fraction and equivalence ratio that successfully induced a secondary flow in the ejector pump. Pressure traces at the inlet and along the ejector pump are used to understand the performance of the ejector pump. The induced secondary flow is found to be approximately triple the primary detonation flow. Fill fraction and equivalence ratio are found to affect the performance of the ejector. High fill fractions and high equivalence ratios results in an oscillatory flow at the ejector inlet. Hydrogen and air are used as the fuel and oxidizer during the experiment with the turbo-charger also. Air flow and pressure at the exit of the compressor are used to evaluate the potential for self-aspirating the PDE. By running two detonation tubes simultaneously through the turbo-charger selfaspiration is achieved. The centrifugal style turbine and compressor of the turbo-charger showed no signs of discoloration or pitting after a 25 minute self-aspiration run where the detonation tube and turbo-charger attained thermal equilibrium. Throughout the course of the testing the turbine experienced 35K plus detonation events and reached a rotational operating speed of 80K rpm.