WHEN striving for means of transportation at high supersonic or hypersonic speeds, either for space travel or for commercial aviation, one has to overcome many challenges [1]. In addition to new propulsion concepts, the integration of the vehicle components, and aerodynamic optimization, one of the most important challenges is the exposure of some aircraft components to extremely high aerothermal loads (5 MW= m2 or more than 3000 K wall temperature possible at a flight Mach number of 8 [1]). These loads are especially apparent at the nose, in the leading-edge region of the plane’s wings, and within the propulsion systems. Here, classical materials like metals or simple ceramics can no longer be used because they would thermally and structurally fail. Hence, one is forced to replace these with high-temperature, lightweight components, some of them with active cooling [2]. In this context new porous materials offer very efficient cooling mechanisms such as transpiration cooling and internal cooling within the structure itself. Those materials have to be tested and qualified. When applying transpiration cooling to a porous wall, a coolant film forms over the surface thickening the boundary layer and therefore reducing the temperature gradients at the wall. This will lead to significantly lower wall heatflux. Because of multiple cooling channels with micrometer dimensions within the porous material, there is also an efficient heat exchange mechanism between the

revision received 20 December 2010; accepted for publication 1 March 2011. Copyright© 2011 by the authors. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission. Copies of this paper may be made for personal or internal use, on condition that the copier pay the $10.00 per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923; include the code 0001-1452/11 and $10.00 in correspondence with the CCC.∗ Research Associate, Institute of Aerospace Thermodynamics, Pfaffen-