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Title: Detailed modeling of electron emission for transpiration cooling of hypersonic vehicles

Electron transpiration cooling (ETC) is a recently proposed approach to manage the high heating loads experienced at the sharp leading edges of hypersonic vehicles. Computational fluid dynamics (CFD) can be used to investigate the feasibility of ETC in a hypersonic environment. In this paper, a modeling approach is presented for ETC, which includes developing the boundary conditions for electron emission from the surface, accounting for the space-charge limit effects of the near-wall plasma sheath. The space-charge limit models are assessed using 1D direct-kinetic plasma sheath simulations, taking into account the thermionically emitted electrons from the surface. The simulations agree well with the space-charge limit theory proposed by Takamura et al. for emitted electrons with a finite temperature, especially at low values of wall bias, which validates the use of the theoretical model for the hypersonic CFD code. The CFD code with the analytical sheath models is then used for a test case typical of a leading edge radius in a hypersonic flight environment. The CFD results show that ETC can lower the surface temperature of sharp leading edges of hypersonic vehicles, especially at higher velocities, due to the increase in ionized species enabling higher electron heat extraction from the surface.more » Finally, the CFD results also show that space-charge limit effects can limit the ETC reduction of surface temperatures, in comparison to thermionic emission assuming no effects of the electric field within the sheath.« less
Authors:
ORCiD logo [1] ; ORCiD logo [2] ; ORCiD logo [1]
  1. Univ. of Michigan, Ann Arbor, MI (United States)
  2. Texas A & M Univ., College Station, TX (United States)
Publication Date:
Grant/Contract Number:
SC0001939
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 121; Journal Issue: 5; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Research Org:
Univ. of Michigan, Ann Arbor, MI (United States)
Sponsoring Org:
USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; work functions; materials properties; flow simulations; electron emission; plasma sheaths; finite temperature field theory; cathodes; plasma temperature; electric fields; space charge effects
OSTI Identifier:
1465324
Alternate Identifier(s):
OSTI ID: 1361756

Hanquist, Kyle M., Hara, Kentaro, and Boyd, Iain D.. Detailed modeling of electron emission for transpiration cooling of hypersonic vehicles. United States: N. p., Web. doi:10.1063/1.4974961.
Hanquist, Kyle M., Hara, Kentaro, & Boyd, Iain D.. Detailed modeling of electron emission for transpiration cooling of hypersonic vehicles. United States. doi:10.1063/1.4974961.
Hanquist, Kyle M., Hara, Kentaro, and Boyd, Iain D.. 2017. "Detailed modeling of electron emission for transpiration cooling of hypersonic vehicles". United States. doi:10.1063/1.4974961. https://www.osti.gov/servlets/purl/1465324.
@article{osti_1465324,
title = {Detailed modeling of electron emission for transpiration cooling of hypersonic vehicles},
author = {Hanquist, Kyle M. and Hara, Kentaro and Boyd, Iain D.},
abstractNote = {Electron transpiration cooling (ETC) is a recently proposed approach to manage the high heating loads experienced at the sharp leading edges of hypersonic vehicles. Computational fluid dynamics (CFD) can be used to investigate the feasibility of ETC in a hypersonic environment. In this paper, a modeling approach is presented for ETC, which includes developing the boundary conditions for electron emission from the surface, accounting for the space-charge limit effects of the near-wall plasma sheath. The space-charge limit models are assessed using 1D direct-kinetic plasma sheath simulations, taking into account the thermionically emitted electrons from the surface. The simulations agree well with the space-charge limit theory proposed by Takamura et al. for emitted electrons with a finite temperature, especially at low values of wall bias, which validates the use of the theoretical model for the hypersonic CFD code. The CFD code with the analytical sheath models is then used for a test case typical of a leading edge radius in a hypersonic flight environment. The CFD results show that ETC can lower the surface temperature of sharp leading edges of hypersonic vehicles, especially at higher velocities, due to the increase in ionized species enabling higher electron heat extraction from the surface. Finally, the CFD results also show that space-charge limit effects can limit the ETC reduction of surface temperatures, in comparison to thermionic emission assuming no effects of the electric field within the sheath.},
doi = {10.1063/1.4974961},
journal = {Journal of Applied Physics},
number = 5,
volume = 121,
place = {United States},
year = {2017},
month = {2}
}