This project is part of the Collaborative Research Centre 1029 „TurbIn“ - Substantial efficiency increase in gas turbines through direct use of coupled unsteady combustion and flow dynamics.
In the course of this particular project the influence of a pulsating and highly unsteady turbine flow, which is a result of the novel combustion process, on the film cooling efficiency of a turbine blade shall be examined. The main goal is to ensure the functionality of the film cooling for all resulting boundary conditions and, if possible, to identify means to reduce the necessary secondary cooling massflow which would result in an overall efficiency gain.
The injection of cooling flow generates a uniform film cooling flow along the blade surface which not only blocks off the hot main gas from the surface but also acts as a heat sink as it lowers the mean temperature within the boundary layer. If properly designed and adjusted, the film cooling flow will cover the whole blade surface whereas for an imperfect flow the thermal stress will rapidly damage and/or destroy the blade. It is therefore necessary to examine the influence of both the pressure and velocity fluctuations on the cooling flow field.
An unsteady Low-Speed test facility is used in the beginning to examine the basic influence of the pressure fluctuations on the film cooling. The large scaling of the measurement section and its optical access allows a very good time-resolved and spatial resolution of this influence.
The succeeding experiments will be carried out at the Hot-Acoustic-Testrig (HAT) which will focus on the influence of the pressure fluctuations on film cooling flow for high temperatures.