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VT

VT NASA EPSCoR RID IV Highlighted Project: “Planar Laser Induced Fluorescence Measurements of Reactant and Product Fluxes in Re-entry Relevant Flight Environments”

Recent results obtained in the University of Vermont Plasma Test and Diagnostics Laboratory (PTDL) have shown that reaction rates for critical gas-surface interactions occurring at planetary entry conditions can be determined by measuring the reacting atomic species diffusion fluxes in the boundary using laser-induced fluorescence (LIF). Planar two photon atomic LIF (TALIF) strategies are technically more challenging when compared to single photon LIF experiments targeting molecular species. To our knowledge, planar TALIF measurements of atomic species have not been demonstrated in ground test environments that simulate planetary entry conditions. A state-of-the-art ICCD camera that allows us to measure LIF signals from atomic species has been acquired recently for testing at the PTDL through the assistance of the Vermont NASA EPSCoR Program. Additional major funding for this purchase was supplied by AFOSR for performing separate and independent experimental projects requiring the capabilities of the camera. This state of the art camera captures the atomic species TALIF signal over the entire front face of a sample and the entire thermal boundary layer, providing simultaneous acquisition of radial and axial diffusion gradients. Significant signal to noise levels have already been demonstrated with this newly installed camera and encouraging results within the thermally reacting boundary layer above sample surfaces have been obtained. Temperature and normalized density trends compare well with previously measured pointwise stagnation line chemically reacting boundary layer profiles. These data will be further analyzed to extract gas-surface kinetic reaction rates using a procedure already developed in our lab. These data will be used to guide the development of new physically based models of the important gas-surface interactions that drive stagnation point heat transfer. Such measurements represent an important advancement in understanding thermal protection material response in trajectory relevant flight environments, with application to a number of planetary atmospheres.

Testing of NASA flexible thermal protection systems material in UVM’s 30 kW Inductively Coupled Plasma Facility; the facility emulates Mars atmospheric entry heating and the ICCD camera allows acquisition of 2D field views of atomic species populations present.

www.nasa.gov/epscor/stimuli

Jason Meyers, Science PI, Research Assistant Professor, School of Engineering, University of Vermont NASA EPSCoR Stimuli 2014-15

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EPSCoR Stimuli 2014-15  

NASA Office of Education’s Aerospace Research & Career Development (ARCD) is pleased to release NASA EPSCoR Stimuli, a collection of univers...

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