Heat transfer in driven cavities with application to turbine structures

In the harsh environment inside a jet engine, the turbine exhaust is one of the most critical areas in terms of high temperatures. The structure material must be able to handle the exposure of very high static temperatures as well as fast heating and cooling, creating temperature gradients. The scope of this work is to further investigate the crucial so called pocket area and the influence of leakage flows on the heat transfer on the turbine structure. The tool for this analysis is computer simulation using CFD. Different amounts of leakage flow is tested in various 2D simulations, and then the results are set as input values in a 3D case. A new 3D model layout is suggested. The results show that the leakage flows do affect the flow patterns and the heat transfer in the investigated area, with in some cases up to 100% higher HTC2 compared to simulations done without leakage flows. The results presented in this report should only be compared to each other. To obtain quantative correct results, input data must be refined for instance. Hence, further investigations, both simulations and actual measurements in this area must be done to achieve a complete understanding. This work is however one step in the right direction, showing that the leakage flows can not be neglected.

Author: Nasvall, Henrik

Source: Lulea University of Technology

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