Overtip shock wave structure and its impact on turbine blade tip heat transfer
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In this paper, the transonic flow pattern and its influence on heat transfer on a high-pressure turbine blade tip are investigated using experimental and computational methods. Spatially resolved heat transfer data are obtained at conditions representative of a single-stage high-pressure turbine blade (Mexit=1.0, Reexit=1.27×106, gap=1.5% chord) using the transient infrared thermography technique within the Oxford high speed linear cascade research facility. Computational fluid dynamics (CFD) predictions are conducted using the Rolls-Royce HYDRA/PADRAM suite. The CFD solver is able to capture most of the spatial heat flux variations and gives prediction results, which compare well with the experimental data. The results show that the majority of the blade tip experiences a supersonic flow with peak Mach number reaching 1.8. Unlike other low-speed data in the open literature, the turbine blade tip heat transfer is greatly influenced by the shock wave structure inside the tip gap. Obliqu
Experimental investigation into the impact of crossflow on the coherent unsteadiness within film coo
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he current paper investigates the impact of spanwise orientated crossflow on the coherent unsteadiness within film cooling flows. Both cylindrical and shaped cooling holes, located on a blade pressure surface, are studied. The range of blowing ratios considered is 0.7-1.8 and the crossflow velocity is up to 0.8 times the bulk jet velocity. High Speed Photography and Hot Wire Anemometry are used to observe the presence of coherent unsteadiness, both immediately downstream of the hole exit and within the cooling hole tube.
Effect of Cooling Injection on Transonic Tip Flows
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In this paper, the effect of cooling injection on the aerodynamics of tip flows in transonic turbines is investigated. Experiments are performed using an idealized model of a transonic tip flow. Schlieren photography, probe, and surface pressure measurements are used to determine the transonic tip flow structure and to validate the computational method. Computational simulations are performed to investigate the effects of cooling injection in a transonic blade environment. The results show that cooling injection has the potential to reduce overtip leakage loss.
The Role of Dense Gas Dynamics on Organic Rankine Cycle Turbine Performance
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In this paper, we investigate the real gas flows which occur within organic Rankine cycle (ORC) turbines. A new method for the design of nozzles operating with dense gases is discussed, and applied to the case of a high pressure ratio turbine vane. A Navier-Stokes method, which uses equations of states for a variety of working fluids typical of ORC turbines, is then applied to the turbine vanes to determine the vane performance. The results suggest that the choice of working fluid has a significant influence on the turbine efficiency.