Date of Award

12-2017

Degree Type

Thesis

Degree Name

Master of Science in Aeronautics and Astronautics

Department

Aeronautics and Astronautics

Committee Chair

Michael Grant

Committee Member 1

Gregory Blaisdell

Committee Member 2

James Longuski

Abstract

A significant factor that currently limits exploration of Mars is the limited payload mass that can be safely placed on the Martian surface. Current systems have only demonstrated successful landing of up to 2 metric tons of payload mass on Mars as seen with the Mars Science Laboratory (MSL). Requirements for future manned missions to Mars will probably require up to 40 metric tons of payload mass in a single descent vehicle. While inflatable and rigid aerodynamic decelerators provide a solution to this problem, supersonic retro-propulsion (SRP) boasts greater simplicity of design as well as improved targeting control. Furthermore, descent vehicles using exclusively SRP could potentially be used as efficient Mars ascent vehicles (MAV). Research into the interaction between the flow of a retro-rocket and the oncoming supersonic flow has revealed that SRP can provide drag modulation effects in addition to the inherent drag of a conical aeroshell. This shows that there is benefit to SRP beyond a purely propulsive contribution to deceleration by allowing for drag retention and even drag augmentation. However, with some SRP configurations, increasing thrust too much proves to cancel out the drag force and even going so far as to reduce the drag on the aeroshell. This study examines an alternative approach for SRP, a toroidal aerospike engine that uses the body of the vehicle as part of the engine. This nozzle configuration delays drag reduction on the aeroshell while increasing thrust due to its peripheral plume structure without providing any drag augmentation. The analysis of this configuration involves computational fluid dynamics (CFD) using OpenFOAM, an open source CFD solver, shown to somewhat model SRP flows. While it has difficulty in properly modelling the flow interaction between the jet plumes and the oncoming flow, trends in fore-body pressure distribution found in experimental data and other CFD based studies are matched.

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