Study of Plume Impingement Effects in the Lunar Lander Environment

Abstract

Abstract. Plume impingement effects from the descent and ascent engine firings of the Lunar Lander were analyzed in support of the Lunar Architecture Team under the Constellation Program. The descent stage analysis was performed to obtain shear and pressure forces on the lunar surface as well as velocity and density profiles in the flow field in an effort to understand lunar soil erosion and ejected soil impact damage which was analyzed as part of a separate study. A Computational Fluid Dynamics (CFD)/Direct Simulation Monte Carlo (DSMC) decoupled methodology was used with the Bird continuum breakdown parameter to distinguish the continuum flow from the rarefied flow. The ascent stage analysis was performed to ascertain the forces and moments acting on the Lunar Lander Ascent Module due to the firing of the main engine on take-off. The Reacting and Multiphase Program (RAMP) method of characteristics (MOC) code was used to model the continuum region of the nozzle plume, and the DSMC Analysis Code (DAC) was used to model the impingement results in the rarefied region. The ascent module (AM) was analyzed for various pitch and yaw rotations and for various heights in relation to the descent module (DM). For the ascent stage analysis, the plume inflow boundary was located near the nozzle exit plane in a region where the flow number density was large enough to make the DSMC solution computationally expensive. Therefore, a scaling coefficient was used to make the DSMC solution more computationally manageable. An analysis of the effects of this scaling technique was performed. Because the inflow boundary was near the nozzle exit plane, another analysis was performed investigating three different inflow contours to determine the effects of the flow expansion around the nozzle lip on the final plume impingement results.

Plume Impingement Analysis for the European Service Module Propulsion System

“…[8][9] For example, the DSMC Analysis Code (DAC) has been applied to model plumes for several different programs including plume impingement on the ISS, the Orion SM RCS engines, and the Altair lunar lander ascent engine among others. [10][11][12] These efforts have shown that DSMC is a viable method to simulate and analyze plume flows and resulting plume impingement. IEMC uses the variable hard sphere (VHS) collision model and the energy transfer treatment between molecules and walls is modeled after Borgnakke and Larsen.…”

Green Propellant Infusion Mission Program Development and Technology Maturation

“…Other DSMC implementations have been successfully used for plume flow and plume impingement studies 26,27 . For example, the DSMC Analysis Code (DAC) has been applied to model plumes for several different programs including plume impingement on the International Space Station, the Orion SM RCS engines, and the Altair lunar lander ascent engine among others 28,29,30 .…”

Investigation on a coupled Navier–Stokes–Direct Simulation Monte Carlo method for the simulation of plume flowfield of a conical nozzle

“…He set the interface just after the nozzle throat and used the NS macroscopic properties as the input of DSMC [16]. Marichalar et al used a CFD/DSMC decoupled methodology to analyze plume impingement effects from the descent and ascent engine firings of the Lunar Lander [18]. Marichalar et al used a CFD/DSMC decoupled methodology to analyze plume impingement effects from the descent and ascent engine firings of the Lunar Lander [18].…”

“…Ivanov performed a decoupled NS-DSMC approach to study the backflow of nozzle plumes expanding into vacuum [17]. Marichalar et al used a CFD/DSMC decoupled methodology to analyze plume impingement effects from the descent and ascent engine firings of the Lunar Lander [18]. Among all the decoupled studies, the interfaces between DSMC and continuum solvers are located more or less artificially; meanwhile, it is hard to ensure that every velocity component normal to the interface is supersonic.…”