Rarefied Plume Modeling for Visors Mission
Abstract
The Virtual Super-resolution Optics with Reconfigurable Swarms (VISORS) mission aims to produce high-resolution images of solar release sites in the solar corona using a distributed telescope. The collected data will be used to investigate the existence of underlying energy release mechanisms [1]. The VISORS telescope is composed of two spacecraft flying in a formation configuration. The optics spacecraft (OSC) hosts the optic system, while the detector spacecraft (DSC) is located behind the OSC in alignment with the Sun and houses a detector. The two modes of operation for the CubeSats are Science Operations Mode and Standby Mode. In Science Operations Mode, the two spacecraft are at a close distance which may make the plume impingement an issue. The cold gas thruster propulsion systems in both the OSC and DSC use R-236fa (HFC) refrigerant. The plume from the system is modeled using SPARTA Direct Simulation Monte Carlo (DSMC) Simulator while the refrigerant itself is modeled using an equivalent particle that closely matches viscosity and specific heat [2]. This work aims to investigate plume propagation for two different flow inputs. The DSMC simulations are performed with the input parameters acquired using the isentropic relations and CFD simulations of the 2D axisymmetric nozzle flow. Additionally, the DSMC results are compared to the Boynton-Simons, Roberts-South, and Gerasimov analytical plume models [3]-[14]. The uniform (isentropic-based) and non-uniform (CFD-based) inputs and the resulting plumes were compared, and differences were observed. These differences resulted from non-isentropic behavior of the flow in the nozzle obtained from the CFD simulation. The influence from the nozzle walls was found to be substantial enough to not be ignored. Additionally, it was found that the way a DSMC input is acquired makes a difference when comparing the resulting DSMC plume to the analytical model plume. From the DSMC plume simulations, the Gerasimov model matched the best for the non-uniform, CFD-based input. This is because its assumptions of a supersonic, ideal gas plume were easily met.
Degree
M.Sc.
Advisors
Alexeenko, Purdue University.
Subject Area
Energy|Aerospace engineering|Astronomy|Fluid mechanics|Mathematics|Mechanics|Optics
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