Cooled Vane Heat Transfer

Abstract

This Master’s thesis project was carried out at the division of Engine Systems at GKN Aerospace, Trollhättan during the spring of 2016. In the project, jet impingement cooling with application to a cooled turbine inlet guide vane was studied with the purpose of developing and validating a model for the thermal load of the vane. As a start, a 2D model of a single slot jet was created and the predicted data compared to experimental data. This comparison showed that the choice of turbulence model highly influenced the results and variations of the k−w model were considered most accurate. When extending this model to include a row of several jets, the assumption of a two-dimensional flow behaviour was found limiting. In the next step, a validation case of a single axisymmetric jet was performed. Area-average values of the differences between the predicted values and the experimental data used in the two validation cases were calculated and determined to maximally 15%. Based on findings from the two validation cases, a model of an array of circular jets was created. Simulations with the jet array model showed that the jet inlet temperature was an acceptable choice of reference temperature. By comparing the results for models with two different jet inlet diameters it was found possible to assume a uniform behaviour of the non-dimensional parameters in the system when scaling up or down the system. Different heat transfer correlations for the heat transfer at the impingement surface were evaluated and some parameters could be singled out as especially important. This included the spacing between the inlets, whereas the effect of crossflow in the array was considered minor. The evaluation indicated that it is possible to to estimate the thermal load by the use of heat transfer correlations if relevant parameters are included.