High-Fidelity Simulation of Dynamic Weakly Ionized Plasma Phenomena

In the Phase I program, we will design an experiment/test article, and test/validate instrumentation and diagnostics, to be used to obtain plasma properties about a hypersonic vehicle having characteristics and features of the RAM-C flight vehicle. The test model is to be installed and tested in the LENS-XX facility (in Phase II) and experimental planning will be supported by detailed numerical simulations. Langmuir probe and RF transmission attenuation measurements will be used to measure the electron distribution about the body. Numerical simulations will include predicting products released by a phenolic graphite (or other) charring ablator including trace alkali products which impact electron density levels in the plasma layer. Electron distribution predictions will use combined charged species / ablation product kinetics with NLTE models. Due short shock tunnel tests times, the test model will have alkaline impurities injected in accordance with levels based on the numerical studies with an ablator at the simulated flight conditions of interest. In addition to formulating a test program for a full/large scale model at nominally duplicated flight conditions, a code validation plan will be initiated making use of the new CRAVE web-based validation tool under development for the Air Force. BENEFIT: A primary benefit of this program is to obtain high quality data of plasma properties in a large scale test facility providing greater details and higher accuracy than obtainable in flight measurements, at a much lower cost. Data will be used to validate the codes being used to simulate these flow, permitting them to study approaches for remedying the blackout problem. Experimental data obtained will be made available through a web-based commercial code validation tool, CRAVE. This tool stores the data sets and benchmark solutions (grids, solution files, etc.) and contains GUI automation and specialized scripts for each data set so that comparisons can be made on a fully-automated basis. CRAVE was developed under Air Force support for high-speed aero-propulsive data sets, is being extended to include high-speed transitional data under an AFOSR program, and will be further extended to include hypersonic plasma date sets under this program. Other avenues for commercialization include additional experimental work focusing on remedying the "blackout problem" by varied innovative concepts, and, further commercialization of CRAFT Tech CFD codes having a unified continuum/DSMC model for RV/Planetary Entry problems that extends into the Wake, includes ablative products, and contains RF/RCS capabilities.