Performance of cascade of blades in two-phase flow, 1

A cascade flow, which is the most fundamental phenomenon in turbo-machinery, is calculated numerically under bubbly two-phase conditions. The governing equations for two-phase flow are formulated with emphasis on local density distribution and sound velocity distribution caused by the slippage between the bubbles and the surrounding liquid. The numerical results reveal some characteristics of the bubbly blade to blade flow. The flow has the characteristics of a compressible flow whose pressure and Mach number have a wide distribution. The void fraction, around the stagnation point of the blade decreases due to the slippage driven by the pressure gradient, and the flow around the stagnation point becomes similar to an incompressible flow. The pressure recovery on the blade surface decreases due to accumulated voids in the low pressure part on the blade. The relaxation zone of the shock wave becomes thicker due to the slippage. (author)