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 “extreme environments” 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.
Potential NASA commercial applications include all Lunar and Mars lander development projects and missions landing on asteroids and other objects. Mars lander plume-surface analysis will be provided to propulsive Entry, Descent, Landing and Ascent systems integration teams. Lunar lander customers include small commercial landers and instrument payloads under the CLEPS program. Robotic precursors and human landers operating from the Lunar Gateway Station will require landing debris environments risk analysis for landers and surrounding assets.
Potential non-NASA applications include a wide range of sand and dust related military and civilian applications such as rotorcraft sand/dust brownout and engine dust ingestion. In addition, multiphase flows occur in many applications in chemical, and fossil-energy conversion industries where accurate modeling of particle shape play a huge role in the flow behavior of real particulate systems.