Experimentelle und numerische Methoden zur Untersuchung einer konvektionsgekühlten Turbinenschaufel unter realen Temperaturbedingungen

This work is focused on the advanced convection cooling for the application in medium power class gas turbine blades. Experimental and numerical methods were set up to analyse the thermal load of the blade at realistic engine operating temperature conditions. The experiments were carried out at the hot gas linear cascade test rig of the Institute of Jet Propulsion and Turbomachinery of the RWTH Aachen at hot gas temperaturesup to 1273 K. Furthermore, an infrared (IR) measurement system was developed and validated to measure surface temperature distributions of the blade. The experiments delivered boundary conditions and validation data for conjugate heat transfer (CHT) and finite element method (FEM) calculations, which have a lower level of detail. The impact of the inner and outer flow characteristics as well as of radiation from the hot gas path on the thermal load of the blade was analysed in detail using both numerical methods. Particular interest was set on the evaluation of radiation effects. The accuracy of the numerical methods was evaluated by means of the measured blade temperatures via thermocouples.The blade temperature distribution was dominated by the characteristics of the cooling system. In the midsection of the blade, the measured and calculated temperature distributions were in good agreement. The temperature deviations were reduced by up to 50% when including radiation. The blade temperature level was increased by radiation, while the surface temperature distribution remained nearly equal. This was also observed forthe level and distribution of the temperature gradients in the blade material. Neglecting radiation led to an overprediction of the cooling effectiveness. Both numerical methods enable the detailed investigation of the turbine blade thermal load. They are eligible for different design steps of convection cooling systems due to their different computational cost and level of detail. The used experimental and numerical methods are applicable to other cooling systems