TMF tests: Optical heating, thermography and deformation measurement of combustion chamber wall structures

Abstract

Optical measurement possibilities for actively cooled thermally loaded wall structures of rocket engines by means of Thermo-Mechanical Fatigue (TMF) tests - aiming at the creation of validation data for CFD, thermal, structural and life time analyses are discussed in this paper. During a TMF test, only a small section of the hot gas wall of the real engine (the so called TMF panel) is tested. For such a TMF panel, realistic cooling conditions similar to a full scale rocket engine are chosen. The 2d measurement of the thermal field of the heat loaded structure provides (together with the measurement of the temperature, pressure and mass flow rate of the coolant of the TMF panel) data for the combined validation of the CFD analysis of the coolant flow and the thermal analysis of the wall structure. The measurement of the deformation of the thermally loaded structure provides (together with the already determined temperature distribution and the above mentioned pressure measurements of the cooling channels) data for the validation of the structural analysis of the thermally loaded structure. Counting the number of laser loading cycles (laser on-off) until the TMF panel fails (by cracks appearing on the laser loaded side of the cooling channels) provides data for the validation of (either post processing or damage parameter based) life time analyses of thermally loaded structures.