Secondary Flow In A Viscous Vortex

Secondary Flow in a Viscous Vortex

The decay for t> 0 of a potential swirling flow is studied at t = 0, when a constant positive value is suddenly imposed on the kinematic viscosity. The flow at this instant is taken to be a potential vortex swirling on top of an infinite stationary horizontal plate. The fluid is assumed to have a constant density, and the flow is laminar and axially symmetric. The interaction of the axial boundary layer flow and the plate boundary layer is studied.

A Visualization Study of Secondary Flows in Cascades

Flow-visualization techniques are employed to ascertain the streamline patterns of the nonpotential, secondary flows in the boundary layers of cascades, thereby providing a basis for more extended analyses in turbomachines. The three-dimensional deflection of the end-wall boundary layer results in the formation of a vortex well up in each cascade passage. The size and tightness of the vortex generated depend upon the main flow turning in the cascade passage. Once formed, a vortex resists turning in subsequent blade rows. This results in unfavorable angles of attack and possible flow disturbances on the pressure surfaces of subsequent blade rows when the vortices impinge on these surfaces.

Visualization of Secondary-flow Phenomena in Blade Row