Online

Whitmore, Samuel

Mechanical Engineering

2020

M.S.

During entry into a planetary atmosphere, a blunt body (e.g. a spacecraft) traveling at hypersonic velocity creates a bow shock in front of it. In the highly energetic post shock environment, the body experiences heat transfer due to convective, chemical, and radiative processes. To protect the payload against this heating, a thermal protection system (TPS) is employed. Because a given propulsion system has a set amount of mass that it can launch to orbit, reducing the amount of mass used for TPS is desirable as this mass is freed up for mission-oriented payload. At the present, uncertainties in the flow field cause conservative assumptions to be made regarding this heating, resulting in an oversized TPS. In inductively coupled plasma (ICP) facilities, a quartz tube is inductively heated to create a plasma, which recreates the post shock environment that an entry vehicle experiences. While insightful on their own, to best understand the mechanisms at play in an ICP facility, experiments can be complimented by computational fluid dynamics (CFD) simulation in order to investigate properties which are not easily measured or varied experimentally. In this way, each side of the investigation informs and pushes forward the other. In this thesis, the combustion CFD code YALES2 has been modified and coupled to Mutation++, a high temperature chemistry library, in order to allow simulation of high temperature plasmas. An additional focus has been the modeling of wall induced recombination of atomic species, which is an exothermic process resulting in additional heat transfer to the body. This gas-surface interaction remains poorly understood and is one of the main uncertainties in the modeling of aerothermodynamic effects during atmospheric entries and therefore TPS design. The resulting code has been used to simulate the 30 kW ICP torch at The University of Vermont, and comparisons with experimental data sets show good agreement. In addition, code-to-code comparisons have been performed, benchmarking the developed code against codes previously used to simulate the facility as well as against US3D, a NASA Ames/University of Minnesota developed code used to simulate all aspects of full scale re-entry flight.