New insights into the swirling flow in turbine blade cooling models obtained via magnetic resonance velocimetry

Magnetic Resonance Velocimetry (MRV) allows measurements of the three-dimensional velocity field in complex channels in which no other measurement technique can be applied. In this thesis, a recent engineering problem is used to demonstrate the usefulness of MRV for industrial design processes: the cyclone cooling of turbine blades. Cyclone cooling is a modern cooling concept which employs strongly swirling flows in the internal passages of the turbine blade. MRV provides a powerful means to gain a deeper understanding of the flow behavior in such systems. Based on a comprehensive parameter study with simplified non-rotating cyclone cooling models employing isothermal water as flow medium, it is examined how the flow reacts to changes in the main parameters of the system. A number of new findings are presented which underline the usefulness of MRV for such applications. In brief, it is found that the downstream condition of the cyclone cooling system is one of the most crucial parameters for the robustness of the system. For example, small changes at the channel outlet can lead to significant variations in the flow pattern inside the entire channel, leading to unpredictable changes in the cooling characteristics. Therefore, as a rule of design, the flow has to be made insensitive to these influences. A number of straight-forward measures are presented which provide the necessary conditions. The transferability of these findings from the simplified cyclone cooling models to the real application is verified by means of a numerical simulation and a realistic cyclone cooling system. In conclusion, this thesis demonstrates the potentials of MRV to contribute to quick and accurate design processes in the fluid mechanics industry.