Improved Simulation of Inflow Distortion for Direct-Connect Scramjet Studies

Abstract

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Velocimetry Measurements of a Scramjet Cavity Flameholder with Inlet Distortion

“…This section, referred to as a distortion generator, replicates the flow nonuniformities produced by a flight vehicle through use of either an asymmetrically varying, cross section or the inclusion of ramps and/or air injectors. Good agreement between numerical simulations of flight inlets and experimental testing of prototype distortion generators was demonstrated, validating the design approaches used [10]. Key differences between the flowfields of distorted and undistorted direct-connect facilities were found in pressure and mass flux distributions, implying that optimal fueling strategies may differ significantly between these two configurations [10,11].…”

“…Although freejet testing more accurately simulates flight conditions, direct-connect testing greatly reduces cost and simplifies technical requirements for both the test article and facility, allowing for a much greater variety of instrumentation techniques [9]. Additionally, the direct-connect environment enables testing of flowpaths too large to be accommodated in freejet test facilities [10].…”

“…The locations of these waves will change throughout the vehicle flight envelope and may alter fuel-air mixing and flameholding properties [11]. It is thus desirable to simulate this distortion experimentally, and to date, several studies have investigated this possibility through the use of an additional facility section installed between the nozzle and scramjet flowpath [9][10][11][12]. This section, referred to as a distortion generator, replicates the flow nonuniformities produced by a flight vehicle through use of either an asymmetrically varying, cross section or the inclusion of ramps and/or air injectors.…”

“…Previous experimental investigations of distortion generators have reported only pressure and temperature data [10,11], and due to the lack of velocimetry measurements, the flow physics of simulated inlet distortion has been largely unexplored. Furthermore, although velocimetry measurements have been reported for a number of scramjet flows [13][14][15][16], only the study of Tuttle et al is known to have examined flow inside a cavity flameholder [17], and no study has reported cavity velocimetry in the investigation of inlet distortion.…”

Optimal aerodynamic design of scramjet facility nozzles

“…The severe limitations imposed by the supersonic combustion in hypersonic air-breathing propulsion systems motivates the extensive Computational Fluid Dynamics (CFD) and experimental investigations on the aero-thermal coupling between hypersonic inlets, isolator and combustor [1,2,3,4,5,6]. The CFD approach is somehow privileged and it is also used in designing the test facilities for the experimental investigations.…”