Effects of flow disturbances from cross-stream fuel injection on the drag reduction by boundary layer combustion

Chan, W. Y. K.; Mee, D. J.; Smart, Michael K.; Turner, James J.

doi:10.2514/6.2012-5889

Cited by 7 publications

(15 citation statements)

References 24 publications

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“…The influence of shock tube fill pressure and temperature uncertainties were found to be negligible, and so will not be considered here. Their minimal influence is clearly apparent in the low sensitivity values in These values are similar to those stated in [59,63,66]. Further justification of these values are given here:…”

Section: C2 Uncertainties In Measured Quantitiessupporting

confidence: 74%

“…The uncertainty of which is conservatively estimated as X P SR = X 2 P ,Stag + X 2 P ,Pitot . X P ,Pitot was taken from [59,66] as 8.8 %.…”

Section: C2 Uncertainties In Measured Quantitiesmentioning

confidence: 99%

“…Thus P SR, which does result in a (locally) linear response surface, is used as the third independent variable instead. Previous uncertainty analyses [58,59,66] examined the sensitivities to shock tube fill pressure and temperature, however the resulting uncertainties were found to be negligible compared to that for the three variables in Table 2.2, and are not included here. Shock Speed, m s The standard error for this linear fit is much less than 0.1% for all quantities except radical species concentrations and radial velocity, both of which have very small absolute values.…”

Section: Response Surfacesmentioning

confidence: 99%

“…• Pitot-Stagnation Pressure Ratio: The pitot pressure has traditionally been the third parameter to examine uncertainty in flow variables [59,63,66]. This is because the previous methods of using NENZF and ESTC-j would relax the nozzle exit conditions to the measured pitot pressure.…”

Section: C2 Uncertainties In Measured Quantitiesmentioning

confidence: 99%

“…This appendix follows the methodology and designations from [63], with various adjustments discussed in detail in [58,66].…”

Section: Uncertainty Analysismentioning

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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Section: C2 Uncertainties In Measured Quantitiessupporting

confidence: 74%

“…The uncertainty of which is conservatively estimated as X P SR = X 2 P ,Stag + X 2 P ,Pitot . X P ,Pitot was taken from [59,66] as 8.8 %.…”

Section: C2 Uncertainties In Measured Quantitiesmentioning

confidence: 99%