Combustion Regimes in Inlet-fulled, Low Compression Scramjets

Gehre, Rolf; Wheatley, Vincent; Boyce, Russell

doi:10.2514/6.2015-3507

Cited by 5 publications

(16 citation statements)

References 27 publications

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“…Based on the equilibrium wall model [101] and flam-elet's combustion model [102], compared with traditional LES simulation, this method can avoid the simulated deviation caused by a high Reynolds number in actual working conditions, and accurately simulate the wall temperature of the combustion chamber of a ramjet. Bricalli et al carried out a numerical study [103] on the combustion performance of a three-dimensional air-inlet non-uniform compression scramjet [104], the results of which show that the three-dimensional combustion process of a non-uniform compression scramjet is more complicated than that of a conventional scramjet because the fuel injection method and associated mixing process can cause additional load to the wall of the combustion chamber. Local changes in the fluid will be affected if the combustion process becomes more complex, yet the overall combustion behavior will not be impacted.…”

Section: Thermal Control Systemsmentioning

confidence: 99%

Thermal Protection System and Thermal Management for Combined-Cycle Engine: Review and Prospects

et al. 2019

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Combined-cycle engine is a potential propulsion system for hypersonic aircraft. To ensure long-term, normal operation of combined-cycle engine under the harsh environment of high thermal load, it is of great significance to study the thermal protection and management of the propulsion system. In this study, the objective and development status of thermal protection and thermal management systems for the combined-cycle propulsion system were described. The latest research progresses of thermal protection, thermal barrier coating, and thermal management system of the combined-cycle propulsion system were summarized. Moreover, the problems and shortcoming in current researches were summarized. In addition, a prospect for the future development of thermal protection and management of the combined-cycle propulsion system was presented, pointing out a direction of great value and vital research significance to thermal protection and management of the combined-cycle propulsion system.

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Section: Thermal Control Systemsmentioning

confidence: 99%

Thermal Protection System and Thermal Management for Combined-Cycle Engine: Review and Prospects

et al. 2019

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“…Figure 17 shows that the convective Mach number increases with the molar mass of the injected gas, enhancing the stability of the resulting injection layer. Equation (9) indicates that the value of γ is also important in determining the convective velocity. This effect can be observed as y → ∞; in Fig.…”

Section: Instability Analysismentioning

confidence: 99%

“…Introduction I NJECTION into hypersonic boundary layers is a potential enabling technology for future high-speed vehicles. Two promising applications, localized transpiration cooling [1][2][3][4][5] and fuel injection in scramjet inlets [6][7][8][9][10], are potentially enabling technologies for future high-speed vehicles and are active areas of research. For both of these applications the stability properties of the boundary layer downstream of the injection location, called the injection layer in this work for clarity purposes, are important.…”

mentioning

confidence: 99%

Stability of Supersonic Flow with Injection

Schmidt

Shepherd

2019

AIAA Journal

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Gas injection into supersonic flow past a 5°half-angle cone is studied with three injected gases: helium, nitrogen, and RC318. Experiments are performed in a Mach 4 Ludwieg tube with nitrogen as the free stream gas. The injector section is shaped to admit a "tuned" injection rate where the displacement created by injection counteracts the effects created by the injector geometry. A high-speed schlieren imaging system with a framing rate of 290 kHz is used to study the instability in the region of flow downstream of injection, referred to as the injection layer. Measurements of wavelength, convective speed, and frequency of the instability waves were made. The stability characteristics of the injection layer are found to be very similar to those of a shear layer. The findings of this work suggest that shear layer modes should be a primary concern for future stability analyses of supersonic flow with injection.

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“…[21,72]. For the purposes of this research, Reynolds-Averaged Navier-Stokes (RANS) simulations were sufficient to simulate the trends of pressure rise for each fuelling case.…”

Section: Numerical Solvermentioning

confidence: 99%

“…This is particularly advantageous at high Mach number conditions, where ignition and reaction lengths become very large. Additionally, interaction between fuel plumes and the inlet shock/expansion systems has been found to dramatically increase mixing for inlet-fuelled engines [21]. To encourage penetration of fuel within the core flow, fuel is typically injected using porthole injection.…”

Section: Fuel Injectionmentioning

confidence: 99%

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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Combustion Regimes in Inlet-fulled, Low Compression Scramjets

Cited by 5 publications

References 27 publications

Thermal Protection System and Thermal Management for Combined-Cycle Engine: Review and Prospects

Thermal Protection System and Thermal Management for Combined-Cycle Engine: Review and Prospects

Stability of Supersonic Flow with Injection

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

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