||Wright-Patterson AFB, OH 454337542
The current state-of-the-art in hypersonic air-breathing propulsion system development relies heavily on a combination of ground tests and numerical simulations. Generally, wall measurements (e.g., pressure, temperature, and heat flux) dominate the instrumentation suite available in most ground test facilities. If in-stream information (typically pitot pressure) is available, it is usually sparse and is generally available only at the inflow and outflow planes of the test article. While valuable for various analyses, these types of information provide little or no detailed descriptions of the mean and turbulent velocity fields, the turbulence-chemistry interactions, or the local state properties within the device. Advanced optical diagnostics are needed for in situ measurements of the parameters (and others) with both temporal and spatial resolution. Preferred diagnostic approaches will use low-power fiber-coupled light source and detector hardware strategies that have an evolutionary path to flightworthy sensors. The research will investigate all aspects of optical diagnostic development for hypersonic flows in scramjet inlets, isolators, and combustors. These aspects include use of novel advanced light source and fiber technology, rapid signal processing for real-time feedback to operators, approaches to tomography, detailed comparison with advanced computational fluid dynamics efforts, and integration into engine control strategies. Specific optical processes to be considered include (but are not limited to) absorption, dual-beam shadowgraphy, and scintillation.
Crow AJ, Boyd ID, Liu J, Brown MS: "Thermal Radiative Simulations and Measurements of the HIFiRE Direct Connect Rig," Journal of Propulsion and Power, (2014), http://arc.aiaa.org/doi/abs/10.2514/1.B35207
Hypersonics; Scramjets; Diode laser; Fiber optics; Molecular absorption; Tomography; Scintillation;