The presented study deals with the internal cooling of turbine blades by swirling flow. The sensitivity of this flow type is investigated towards Reynolds number, swirl intensity and the common geometric features of cooling ducts. The flow system consists of a straight and round channel that is attached to a tangential-type swirl generator. The channel outlet features various orifices and 180-degree-bends. The investigated Reynolds number range is Re = 2000…32000 and the geometric swirl numbers are S* = 1,3,5. The experiments were carried out with Magnetic Resonance Velocimetry for which water was used as flow medium. As the main outcome, it was found that the investigated flows are highly sensitive to the conditions at the outlet of the channel. But it was also discovered that for some channel outlets the flow field remains the same. The associated flow type features a favorable topology for heat transfer: The majority of mass is transported in the annular region close to the channel walls. Together with its high robustness, it is regarded as an applicable type for the internal cooling of turbine blades. A Large Eddy Simulation was conducted to analyze the heat transfer characteristic of this flow. For S*=3 and Re=20000, the simulation showed an averaged Nusselt number increase of factor 4.7 compared to fully-developed flow. However, a pressure loss increase of factor 43 must be considered as well. The presented measurements and simulations have led to a further understanding of swirling flows and proved these flows advantageous for the internal cooling of turbine blades.

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