Measurement and Modeling of High Speed Polydisperse Granular Flow Under Plume/Surface Interaction Conditions

The liberation of dust and debris particles caused by rocket plume flow from spacecraft landing on the unprepared regolith of the Moon, Mars, and other extra-terrestrial destinations poses a high risk for robotic and human exploration activities. This regolith particle flow induced by a spacecraft landing occurs in a combination of ldquo;extreme environmentsrdquo; that combine low gravity, little or no atmosphere, with rocket exhaust gas flow that is supersonic and partially rarefied, and unusual mechanical properties of the regolith. Of these environmental factors, characterizing the regolith granular material fluidic behavior and gas-granular interactions is the most complex and least developed. In the proposed effort an integrated project team consisting of CFD Research, University of Michigan and Johns Hopkins University will develop an integrated approach for developing a combined measurement and modeling methodology to further improve accuracy of the gas granular flow solvers used for analysis and design by NASA engineers. Targeted experiments will be conducted to analyze gas-particle flows in high-speed and low-speed dilute conditions on both monodisperse and polydisperse particulate mixtures. Crucial data for model validation such as particle velocity fluctuations, particle concentrations and bulk velocities will be obtained. Subsequently, model improvements will be made for both, Eulerian-Lagrangian and Eulerian two-fluid simulation approaches and improved capabilities demonstrated. Particular effort will be made toward advancing the granular phase constitutive relations the numerical framework relies upon for polydisperse compressible flows.