Supersonic Combustion Processes in a Premixed Three-Dimensional Nonuniform-Compression Scramjet Engine

Bricalli, Mathew; Brown, Melrose; Boyce, Russell

doi:10.2514/1.j052640

Cited by 22 publications

(35 citation statements)

References 24 publications

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“…Curran [34] discussed the various studies produced by Ferri and Fox [11,16], which will be examined here along with a 2D analysis by Billig et al [12]. A more recent examination of thermal compression by Bricalli et al [13,14] will also be presented.…”

Section: Thermal Compression Studiesmentioning

confidence: 98%

“…The thermal compression tehcnique looked extremely promising when it was examined in the 1960s and 1970s; however, it was not developed further until numerical work by Bricalli et al [13,14]. Bricalli et al showed that non-uniformities could be used in a three-dimensional flow field to dramatically improve performance over a similar two-dimensional engine.…”

Section: Motivationmentioning

confidence: 99%

“…This enables combustion in particular regions of the engine, whilst suppressing it in others, as done numerically in [13]. This method of injecting helium into an air test gas was previously used by [23] to isolate luminosity from atomic O in the freestream.…”

Section: Fuel Injectionmentioning

confidence: 99%

“…However, it should be noted that to achieve such thrust levels, there is a significant level of complexity in engine design, both in combustor layout and injector location. A simpler 3D thermal compression engine geometry was suggested by Bricalli et al in premixed [13] and inlet-fuelled [14] numerical simulations. A constant area combustor was attached to a 3D inlet, consisting of turning angles that vary in the spanwise direction, but have constant gradient in the streamwise direction, as shown in Fig.…”

Section: Thermal Compressionmentioning

confidence: 99%

“…The project presented in this thesis follows on from these studies and examines, experimentally, whether these features increase combustion in a real scramjet engine, based on the design in [13,14].…”

Section: Thermal Compressionmentioning

confidence: 99%

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Experimental Investigation of a 3D Thermal Compression Scramjet Using Advanced Optical Techniques

Vanyai¹

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Scramjet engines are limited in performance due to engine starting problems at low hypersonic speeds. For an accelerating hypersonic vehicle, intake contraction ratios are typically fixed to the low speed starting requirements. This reduces engine performance at higher Mach numbers, where higher contraction ratios are required to efficiently combust flow within a practically-sized combustor.The use of a combustion process called "Thermal Compression" was suggested in the 1960s that could improve the performance of low intake contraction scramjet engines. In such an engine, the flow field is non-uniform within the combustor, with regions of locally high pressure and temperature even at low net intake contraction ratio. The flow properties in these regions are suitable for combustion of air-fuel mixtures, inducing autoignition. As heat is released, increased temperature and pressure are transmitted to the surrounding flow through pressure waves. Conditions in the surrounding flow become suitable for combustion, and this process continues until combustion completes throughout the entire flow field.This work presents results from experimental and numerical analysis of a three-dimensional, thermal compression scramjet engine at two high Mach number flight conditions. Experiments were conducted in the T4 Shock Tunnel at The University of Queensland. The tunnel test gas simulated flow that had been processed by an engine forebody at either 8.0• or 8.8• angle of attack, in an equivalent flight condition of Mach 10, 50 kPa dynamic pressure.An engine test model was developed to examine the effect of thermal compression on combustion-induced pressure rise at these inflow conditions. Non-uniform combustor flow was generated using a three-dimensional intake with a ramp angle that varied in the spanwise direction. This produced a low compression side and a high compression side throughout the scramjet engine. Fuel injection plenums were split such that different gases could be injected in either the low compression or high compression side. Combustion was induced by injecting hydrogen fuel, or suppressed by injecting helium.i Pressure measurements were taken along the streamwise length of the engine, in three spanwise locations. Optical techniques, including emission and laser-induced fluorescence (LIF) methods, were used to visualise the distribution of OH radicals throughout the combustor. These experimental results were then compared to fully-combusting, RANS CFD simulations.The influence of thermal compression was determined by comparing combustion-induced pressure rise in the fully-fuelled case to the sum of both cases where combustion was suppressed on each side of the engine. It was found that for the forebody angle of 8.8• case, thermal compression increased pressure rise by 14.4 ± 6.0 % and 6.7 ± 6.2 % for fuel-air equivalence ratios of φ = 0.8 and φ = 1.0 respectively. Emission from OH radicals, which is qualitatively indicative of combustion, also increased by 19 -54 % in the rear of the combustor. Numerica...

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