Feasibility assessment of magnetohydrodynamics for hypersonic trajectory control for planetary exploration applications

Magnetohydrodynamics can be harnessed to augment aerodynamic drag during planetary entry or aerocapture. The increased drag can be used for precision targeting or enabling larger payloads to reach the surface. The magnitude of the magnetohydrodynamic force depends on the electrical conductivity of the post-shock flow, which is difficult to model. This thesis develops two electrical conductivity databases for Mars and Venus entries. The results of the electrical conductivity databases are used to evaluate magnet configurations using state-of-the-art magnet technology for magnetohydrodynamic trajectory control. One database documents the electrical conductivity around the vehicle in rarefied flow. Direct simulation Monte Carlo techniques are used to solve for flow field properties around the spacecraft. The results of Direct simulation Monte Carlo are used to estimate the electrical conductivity across a range of freestream densities and velocities and for different vehicle sizes. The location and magnitude of the peak conductivity in the shock layer are documented. The electrical conductivity increases linearly with velocity, and the conductivity profile in the shock layer remains constant across the range of velocities considered. The conductivity decreases with altitude. As the density increases, the location of peak conductivity moves closer to the stagnation line. Additionally, large vehicles have higher electrical conductivity in the shock layer. The conductivity trends can be useful for identifying the optimal magnet placement to maximize magnetohydrodynamic forces. A similar electrical conductivity database is created for continuum flow using computational fluid dynamics. The continuum electrical conductivity database covers the range of freestream conditions that would be expected for an entry or aerocapture at Mars and Venus. In addition to the electrical conductivity, the database documents the Hall parameter for each freestream condition to determine where the Hall effect can be neglected and when it should be taken into account. A code-to-code comparison between direct simulation Monte Carlo and computational fluid dynamics shows reasonable agreement between the two computation methods. The electrical conductivity results allow the magnetohydrodynamic force to be efficiently calculated for any magnetic field. A feasibility study is performed on four different magnet configurations: an array of small magnets, a large non-superconducting magnet, a large superconducting magnet, and a uniform field. Current state-of-the-art hardware limitations are accounted for in designing each magnetic field, and the resulting force from each magnet configuration is computed. A new magnetohydrodynamics force model is proposed that uses the electrical conductivity databases to estimate the magnetohydrodynamic force using any magnetic field. Of all the magnet configurations considered, the superconducting magnet is the only one that can provide sufficient force to affect a trajectory. The magnetohydrodynamic forces are compared with literature when available. The force results agree with more complex models in literature within an order of magnitude. For each magnet configuration, implementation challenges related to mass, power, and thermal management are discussed. The large power draw and heat dissipation make non-superconducting magnets challenging to implement for many entry missions. Superconducting magnets require low mass, but the cryogenic cooling, high power input, and high cost make them unattractive for space missions in the near future. Although magnetohydrodynamic drag may not be useful during entry, it could be used to reduce the time for an aerobraking campaign. The magnetohydrodynamic force has approximately the same magnitude as aerodynamic drag at some low-density conditions, so it could be useful in an aerobraking environment. The Venus Express orbit is used to estimate the magnetohydrodynamic force at the highest velocity and highest density condition during the aerobraking mission. Electrons are assumed to stay near their parent ions to make the simulation computationally feasible, but the magnetohydrodynamic force cannot be accurately modeled in extremely low-density flows without a reasonable estimate of the electron motion. The utility of magnetohydrodynamics for aerobraking applications could not be determined, but future studies may use the results to simulate electron motion and get a reasonable estimate of the magnetohydrodynamic drag.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Aerospace Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2024

Author dc:creator

• Fawley, Destiny M.

Contributors dc:contributor

• Eggl, Siegfried
• Putnam, Zachary
• D'Souza, Sarah
• Panerai, Francesco
• Ruzic, David
• Rovey, Joshua

• Planetary Entry
• Hypersonic
• Hypersonics
• Cfd
• Dsmc
• Computational Fluid Dynamics
• Direct Simulation Monte Carlo
• Magnetohydrodynamics

Statement dc:rights

• Copyright 2024 Destiny Fawley

Language dc:language

en, eng

Handle dc:identifier

https://hdl.handle.net/2142/127238

OAI record oai:identifier

https://www.ideals.illinois.edu/oai-pmh?verb=GetRecord&metadataPrefix=etdms&identifier=oai%3Awww.ideals.illinois.edu%3A2142%2F127238