Magnetic Resonance Velocimetry of a Turbine Blade With Engine-Representative Internal and Film Cooling Structures

Abstract

As a key technology to ensure turbine survival, blade cooling encompasses a whole range of strategies with ever-increasing geometric complexities. Flow measurement for turbine blades with such intricate internal and external cooling structures is very challenging and calls for non-intrusive, three-dimensional measuring techniques. As a response, this work utilizes magnetic resonance velocimetry (MRV) to measure the velocity field in a scaled turbine blade with engine-representative internal and film cooling structures. Internal cooling structures include leading edge impingement cooling, U-shaped serpentine passage with/without turbulence ribs at blade mid-chord, and trailing edge pin fins. External cooling structures include film holes near the leading edge stagnation point, at the blade tip, and on the trailing edge. Experiments were performed in water and the Reynolds number local to the leading edge, mid-chord, and trailing edge cooling channels falls within the range typically reported in the literature. This is the first time that MRV is used to measure the flow field of a turbine blade with all the typical internal and external cooling geometries combined. The results show that MRV has great capacity in measuring the complex fluid flow associated with blade cooling designs. Vortical flow features in leading edge impingement cooling, and at the U-bends of mid-chord serpentine channel are captured. Interestingly, internal flow around pin fins redistributes the velocity of external flow ejected from trailing edge slots and film holes, indicating strong coupling between the internal and film cooling flow of the turbine blade.