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@PHDTHESIS{Knig:854621,
author = {König, Valentina},
othercontributors = {Müller, Siegfried and Herty, Michael},
title = {{E}ffective boundary conditions for transpiration cooling
applications},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2022-09672},
pages = {1 Online-Ressource : Illustrationen, Diagramme},
year = {2021},
note = {Englische und deutsche Zusammenfassung. - Veröffentlicht
auf dem Publikationsserver der RWTH Aachen University 2022;
Dissertation, RWTH Aachen University, 2021},
abstract = {Using transpiration cooling with carbon/carbon (C/C) thrust
chamberliner is identified as a new innovative cooling
concept that can lead to improvement in advanced rocket
engines. In addition to experiments, computational fluid
dynamics simulations offer an efficient and low
costpossibility to investigate the physical phenomena of
transpiration cooling. In the present work an effective
model is developed that simulates transpiration cooling
taking microscale effects at the interface between ahot gas
flow and a porous medium flow into account without resolving
the microscale pores. The derivation of our general strategy
is based on upscaling and consists of three models: the
multiscale model, the zeroth-order model and the effective
model, where the latter two models operate on the
macroscale. Here the multiscale model captures the local
injection of a coolant through a large number of pore size
injection channels. It is set up to derive appropriate cell
problems on the microscale and to validate the effective
model. For the latter effective boundary conditions are
developed using an upscaling approach. To validate the
effective model numerical computations are presented.
Furthermore, the influence of the microscale characteristics
on the heat transport in turbulent flow over a porous
material is investigated. All computations are based on wind
tunnel experiments performed at the ITLR Stuttgart with a
porous C/C sample produced at the DLR Stuttgart. For the
injection rate F = $0.1\%$ the numerical solutions of the
three modelsare compared to each other in terms of
temperature distribution, wall shear stress, wall heat flux
and cooling efficiency. Numerical computations show that the
predicted cooling efficiency is reduced when using a local
injection (multiscale) in comparison to a uniform injection
(zerothorder). This effect is reflected in the effective
computation. Thus, the effective model provides a more
accurate approximation than the zeroth order solution.
Furthermore, the effective model is significantly more
efficient compared to a fully resolved multiscale
computation. This is confirmed by comparing the amount of
grid cells and computational times.},
cin = {111410 / 110000},
ddc = {510},
cid = {$I:(DE-82)111410_20170801$ / $I:(DE-82)110000_20140620$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2022-09672},
url = {https://publications.rwth-aachen.de/record/854621},
}
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