摘要 :
Uranus and Neptune, known collectively as the Ice Giants, are the only two planets in the solar system that are yet to be explored with a dedicated mission. Planetary entry probe missions to the Ice Giants were proposed in 2010 by...
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Uranus and Neptune, known collectively as the Ice Giants, are the only two planets in the solar system that are yet to be explored with a dedicated mission. Planetary entry probe missions to the Ice Giants were proposed in 2010 by NASA and ESA which prompted a resurgence of interest in experimental simulation of the aeroheating environment that would be encountered by such a spacecraft. More recently, the 2023 - 2032 Decadal Survey recommended that NASA's highest priority new flagship mission should be a Uranus orbiter and probe with a launch date in the early 2030s. The Oxford T6 Stalker tunnel is the only facility in Europe capable of replicating the high speeds required for Ice Giant entry and is therefore a key stepping stone on the path to realising the goal of an Ice Giant mission. In the present work, a 1:10 scaled model of the Galileo probe has been tested at Ice Giant entry conditions. Conditions for nominal composition (85%H_2-15%He), Stalker substituted, and nominal composition with methane (0.5% and 5% CH_4) gas mixtures have been developed and validated for use with a new expansion nozzle via a Pitot rake survey. Test flows with flight equivalent velocities greater than 18 km/s have been produced with test times on the order of 30 μs. Heat flux into the model for the developed conditions has been inferred from temperature measurements with a series of coaxial thermocouples. High speed video, with and without schlieren, has been captured to aid in characterisation of the test conditions.
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Scramjet engines must be designed to operate over a range of Mach numbers. In order to maintain robust starting characteristics at low freestream Mach numbers, the inlet contraction ratio must be minimized, reducing performance at...
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Scramjet engines must be designed to operate over a range of Mach numbers. In order to maintain robust starting characteristics at low freestream Mach numbers, the inlet contraction ratio must be minimized, reducing performance at high Mach numbers. The technique of thermal compression can be used to maintain robust combustion at low mean pressure and temperature, improving the performance of low inlet contraction ratio engines over a range of Mach numbers. This paper examines a scramjet engine with a three-dimensional inlet that induces spanwise gradients of pressure and temperature, producing high inlet compression on one side and low inlet compression on the other. The effect of combustion in each half on pressure throughout the entire flowfield is examined by suppressing combustion on either half of the combustor through injecting either a combusting fuel, hydrogen, or a non-combusting replacement, helium. Two optical techniques are used to examine how the concentration of the OH radical varies throughout the combustor. Images of OH~* Chemiluminescence and OH Planar Laser-Induced Fluorescence (PLIF) map the concentration and production of OH radicals indicating chemical activity throughout the combustion process. The thermal compression effect is isolated, and is shown to increase combustion-induced pressure rise in a scramjet engine.
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摘要 :
Scramjet engines must be designed to operate over a range of Mach numbers. In order to maintain robust starting characteristics at low freestream Mach numbers, the inlet contraction ratio must be minimized, reducing performance at...
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Scramjet engines must be designed to operate over a range of Mach numbers. In order to maintain robust starting characteristics at low freestream Mach numbers, the inlet contraction ratio must be minimized, reducing performance at high Mach numbers. The technique of thermal compression can be used to maintain robust combustion at low mean pressure and temperature, improving the performance of low inlet contraction ratio engines over a range of Mach numbers. This paper examines a scramjet engine with a three-dimensional inlet that induces spanwise gradients of pressure and temperature, producing high inlet compression on one side and low inlet compression on the other. The effect of combustion in each half on pressure throughout the entire flowfield is examined by suppressing combustion on either half of the combustor through injecting either a combusting fuel, hydrogen, or a non-combusting replacement, helium. Two optical techniques are used to examine how the concentration of the OH radical varies throughout the combustor. Images of OH~* Chemiluminescence and OH Planar Laser-Induced Fluorescence (PLIF) map the concentration and production of OH radicals indicating chemical activity throughout the combustion process. The thermal compression effect is isolated, and is shown to increase combustion-induced pressure rise in a scramjet engine.
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Experimental investigations of scramjet combustion are the focus of experimental studies performed in T4 facility at The University of Queensland. The objective of the present study is to develop code support to determine OH tempe...
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Experimental investigations of scramjet combustion are the focus of experimental studies performed in T4 facility at The University of Queensland. The objective of the present study is to develop code support to determine OH temperatures in such high speed flows. For this purpose available source codes, namely SPARTAN and Photaura, had to be extended in order to include OH species in their databases. Validation of the OH modelling in SPARTAN and Photaura was done by comparison with the results of LIFBASE simulations. The results of these codes were compared with the OH~* chemiluminescence spectra obtained using a Mach 9 enthalpy-equivalent flight condition. A two-dimensional scramjet model with a constant-area supersonic combustor was used in the experimental investigation. The OH~* chemiluminescence signal was recorded and the spectrally resolved measurements of the OH~* emission spectra have been conducted in order to characterise the ignition and combustion processes. When compared with the spectrally resolved OH~* emission spectra, the results of spectral simulations demonstrate a very good agreement. The comparison with the experimental data indicate that results of three synthetic spectral simulation can be considered as a consistent representation of the physical phenomena and can serve as a pre-experiment indication of the combustion process studied. The presented results show the possibility of using OH~* chemiluminescence spectra to infer relative temperatures in supersonic combustion. Absolute temperatures can be inferred if the offset between the intensity-versus-temperature functions for OH~* and OH is known.
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摘要 :
Experimental investigations of scramjet combustion are the focus of experimental studies performed in T4 facility at The University of Queensland. The objective of the present study is to develop code support to determine OH tempe...
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Experimental investigations of scramjet combustion are the focus of experimental studies performed in T4 facility at The University of Queensland. The objective of the present study is to develop code support to determine OH temperatures in such high speed flows. For this purpose available source codes, namely SPARTAN and Photaura, had to be extended in order to include OH species in their databases. Validation of the OH modelling in SPARTAN and Photaura was done by comparison with the results of LIFBASE simulations. The results of these codes were compared with the OH~* chemiluminescence spectra obtained using a Mach 9 enthalpy-equivalent flight condition. A two-dimensional scramjet model with a constant-area supersonic combustor was used in the experimental investigation. The OH~* chemiluminescence signal was recorded and the spectrally resolved measurements of the OH~* emission spectra have been conducted in order to characterise the ignition and combustion processes. When compared with the spectrally resolved OH~* emission spectra, the results of spectral simulations demonstrate a very good agreement. The comparison with the experimental data indicate that results of three synthetic spectral simulation can be considered as a consistent representation of the physical phenomena and can serve as a pre-experiment indication of the combustion process studied. The presented results show the possibility of using OH~* chemiluminescence spectra to infer relative temperatures in supersonic combustion. Absolute temperatures can be inferred if the offset between the intensity-versus-temperature functions for OH~* and OH is known.
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