ISBN 978-3-8439-5658-1

978-3-8439-5658-1, Reihe Thermodynamik

Andreas Schwab
A Contribution to Transpiration Cooling for Rocket Combustion Chambers in a Stacked Transpiration Cooling Arrangement

317 Seiten, Dissertation Universität Stuttgart (2025), Softcover, A5

Zusammenfassung / Abstract

High thermal loads on the propulsion systems and economic cost pressures require efficient cooling mechanisms with durable materials for future reusable space transportation systems. These technical demands are encapsulated by transpiration cooling utilizing state of the art ceramic matrix composite (CMC) materials. Despite confirmation of the principle applicability of the cooling technique and materials in rocket engines, a theoretical characterization of the thermophysical mechanisms in an application-oriented stacked combustion chamber setup is remaining.

The current thesis contributes by investigating a multi-functional stacked transpiration cooling arrangement of carbon fiber reinforced carbon materials (C/C). By means of three complementary test cases a combined experimental and numerical approach is pursued. Experiments are conducted in subsonic flow conditions to characterize the overlapping of different kinematic and thermal boundary layer situations, to analyze a modeling of the thermal cold-side boundary conditions, and to identify the influence of the wake flow on the superposition capability of a transpiration cooling system. Numerical Reynolds-averaged Navier-Stokes simulations (RANS) applying the in-house OpenFOAM-based simulation tool spectraFOAM complete this holistic approach.

As a result, firstly, a suitable characterization of the external boundary layer phenomenology in the mixing zone of the transpiration cooling setup is demonstrated. Secondly, an analysis of the overall thermal situation within the porous structure regarding the influence of the cold-side boundary condition on the surface temperatures reveals a good agreement between experimental and numerical data. Thirdly, an initial approach on the superposition principle in transpiration cooling has been conducted. A general applicability of the superposition principle in transpiration cooling is proven valid.