Cyclic Laser Heating and Optical Measurement of Combustion Chamber Wall Structures

Abstract

The inner liner of a regeneratively cooled wall of a main stage rocket combustion chamber is extremely loaded by the high temperature of the hot gas and the pressure difference between the coolant and the hot gas. A cyclic operation of such a chamber usually causes a LFC failure of the wall structure after a very low number of cycles. For the tests presented in this paper, cyclic laser heating is (as replacement for the hot gas) applied to an actively cooled small section of the hot gas wall of the real engine - the so called TMF panel. Optical measurements during such TMF panel tests provide essential validation data for CFD, thermal, structural and life time analyses: 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.