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This study investigates on heat transfer enhancement in pin fin cooling channels. Experiments are conducted in a staggered pin fin array consisting of 15 rows. Heat transfer measurements are conducted in the pin fin cooling channel using the transient liquid crystal technique. The reference temperature is approximated by the fluid bulk temperature, acquired by thermocouples at specific positions. Thermal inertia of the used thermocouples is considered. One other problem that occurs while using relatively long thermocouples in short aspect ratio ducts is the heat conduction along the wires, the so-called stem effect. This can lead to erroneous temperature measurements. The impact of the thermocouple immersion length on the temperature measurement is investigated. A detailed assessment of the space and timewise varying temperature distribution is conducted for the appropriate reference temperature. This paper gives an overview about the experimental setup and the used transient measurement technique. Results are represented in terms of temperature distribution, heat transfer distribution, and averaged Nusselt number at the endwall.

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Hypersonic airliner would be exposed to temperatures that are beyond the limits of classical aircraft materials. In order to handle this problem the latest developments of new materials and composite structures suitable for high temperature application need to be taken into account. The focus of the European Research program ATLLAS is on advanced light-weight, high-temperature material development strongly linked to a high-speed passenger aircraft design. ATLLAS stands for Aerodynamic and Thermal Load Interactions with Lightweight Advanced Materials for High Speed Flight. The 4.5 years program ATLLAS-II is a logical continuation project built upon the experience and technology development gained within ATLLAS-I. The corresponding work related to combustor structures and material integration deals with the opportunity to investigate at academic level, both in basic and relevant environment, different solutions possibly usable to ensure the long range cruise of a high speed airliner. Different materials (UHTC, CMC, metallic) and different cooling techniques (radiation, convective, transpiration) are studied. Available 2 numerical or semi-empirical tools are used to prepare the test, to design the different architectures. A pin fin experiment allows to better know the pressure drop and the heat transfer for different channel patterns with thermal crystal techniques. The ERBURIG K long duration test facility allows to characterize different ceramic matrix composite uncooled samples to realize, at small scale, a long duration (several hours) investigation of cooled ceramic structure in PTAH-SOCAR technology. A multifunctional metallic transpiration cooled HSS panel using Hollow Spheres Stacking as core material was designed and preliminary tested in cold conditions with GN2 and in hot conditions with infra-red lamps under 1 MW/m² heat flux before successful METHYLE testing in supersonic reacting flow. CMC and UHTC materials are used to design, manufacture and test generic fin injectors usable in high speed combustors. Industrial hypersonic METHYLE test facility is used to test in relevant Mach 6 combustor environment CMC and HSS panel as well as advanced fin injectors. Hot and cold permeability of composites is also documented with GN2 and GH2, taking into account the mechanical stress possible effect. Numerical models are used in accordance with the experiments, some examples are also given in the present paper. NomenclatureC/C-SiC = carbon fibre reinforced silicon carbide CFD = computational fluid dynamics CMC = ceramic matrix composite ERBURIG K = Environmental Relevant Burner Rig -Kerosene HSS = Hollow Spheres Stacking (sandwich) FEM = finite elements (mechanical computational) method GN 2 = gaseous nitrogen METHYLE= French acronym for long duration hypersonic technology test facility O 2 = oxygen SiC/SiCN = silicon carbide fibre reinforced silicon carbonitride TLC = Thermochromic Liquid Crystals UHTC = ultra high temperature ceramics

This study investigates on heat transfer enhancement in pin fin cooling channels. Experiments are conducted in a staggered pin fin array consisting of 15 rows. Heat transfer measurements are conducted in the pin fin cooling channel using the transient liquid crystal technique. The reference temperature is approximated by the fluid bulk temperature, acquired by thermocouples at specific positions. Thermal inertia of the used thermocouples is considered. One other problem that occurs while using relatively long thermocouples in short aspect ratio ducts is the heat conduction along the wires, the so called stem effect. This can lead to erroneous temperature measurements. The impact of the thermocouple immersion length on the temperature measurement is investigated. A detailed assessment of the space and time-wise varying temperature distribution is conducted for the appropriate reference temperature. This paper gives an overview about the experimental setup and the used transient measurement technique. Results are represented in terms of temperature distribution, heat transfer distribution and averaged Nusselt number at the endwall.