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Blade lean in axial turbines : model turbine measurements and simulation by a novel numerical method


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Authors

Walker, Peter John 

Description

The effects of blade lean on the flow through axial turbines are investigated. An approximate axi-symmetric analysis is developed which predicts the influence of blade lean on streamline curvature and radial pressure distribution in the vicinity of the blade. The results are confirmed by numerical predictions using a throughflow method which has been modified to include blade lean. The analysis indicates that in an appropriate geometry blade lean may be beneficial in reducing losses. Experimental results from a model turbine with zero lean, straight lean, and compound lean stator blades are presented. These show a two percent improvement in stage efficiency with the compound lean. A novel incompressible time-marching tech niq ue has been developed. This method requires substantially less computer resources than previous incompressible time-marching methods. It propogates the flow condition information contained in a boundary condition into the flow domain in an efficient manner. This is done by multiplying the flux residues by an appropriate matrix. The experimental results from the model turbine are explained using the incompressible time-marching method.

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Qualification

Doctor of Philosophy (PhD)

Awarding Institution

University of Cambridge