Predication of the Flow Field and the Performance for the Unshrouded and Shrouded Centrifugal Impeller

The tip clearance influence of an unshrouded backswept impeller on the three-dimensional viscous flow field and performance was studied numerically by using a fourth-order Rounge-Kutta three-dimensional viscous code. Three-dimensional viscous code was used for the detailed flow field and performance studies of the unshrouded and the shrouded centrifugal impeller. The numerical results reveal that the unshrouded impeller discharge velocity profiles are comparatively smooth at design and off-design operating condition, which is widely different from the well-known jet/wake-type flow pattern. The tip-clearance effect should be properly modeled to predict the impeller flow pattern properly. The performance of the shrouded impeller is better than that of the unshrouded impeller due to the tip clearance.