Investigation for Loss Generation Mechanisms of Flow in Turbomachinery by Using Curved Square Duct (1st Report, Influence of Inlet Velocity Distribution)

The secondary flow within a passage of a turbomachinery exhibits a complex flow pattern by the effects of the centrifugal and the Coriolis forces. In this secondary flow, the passage vortex generates a major part of the losses. However, the mechanism of the loss generation by the secondary flow has not been fully clarified yet. In this point of view, the passage vortex is closely examined by the numerical computations using the curved square ducts as fundamental models for the generation of the passage vortex. The inlet boundary layer thickness and the inlet velocity profiles are chosen as the major parameters affecting the generation of passage vortex in the present study. The computed results exhibited that the passage vortex gave the predominant effects for the generation of loss not only in the breakdown process but also in the development process.