ISBN 9783843918176

978-3-8439-1817-6, Reihe Thermodynamik

Barbara Mayer
Investigations of Pressure Loss and Heat Transfer in a Regular Metallic Porous Structure

136 Seiten, Dissertation Universität Stuttgart (2014), Softcover, A5

Zusammenfassung / Abstract

A constantly growing demand for electricity drives the need for highly efficient and low emitting gas turbines. Thus the gas turbine inlet temperature has to be increased from the current 1,500C to 1,700C. This goal can only be achieved by the improvement of heat transfer and cooling technologies.\par In this thesis a new turbine blade cooling concept, a regular metallic porous structure, is investigated by experiments and numerical simulations.

Steady-state fluid flow and heat transfer experiments were conducted to determine the specific pressure loss, the heat transfer from the wall into the structure, and the thermal contact resistance. Results show that compared to traditional configurations, the analyzed porous media has a 50% to 150% higher thermal performance, specially for low mass flow rates. Transient temperature oscillation tests were used to obtain the volumetric heat transfer coefficient describing the heat transfer characteristics within the structure.

Based on the experimental results correlations for pressure loss and heat transfer were developed. Since the range of the conducted experiments was limited and the fact that they only deliver macroscopic but no cell based information, numerical simulations were carried out to determine local pressure loss and heat transfer. For the calculations two different approaches were followed: 3D CFD calculations, fully resolving the structure in grids, and a porous domain model, treating the structure as a black box.

To assess whether the porous structure can be improved to cope with the trade-off between pressure loss and heat transfer in porous media, the geometry of the structure was optimized by an extreme value determination.