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ISSN オンライン: 2642-0554

TRANSITION MECHANISM AND ITS CONTROL IN BOUNDARY LAYERS UNDER CENTRIFUGAL FORCES

Nina F. Yurchenko
Institute of Hydromechanics of National Academy of Sciences of Ukraine, 8/4, Zhelyabov St., Kyiv, 03057, Ukraine

要約

Interaction of centrifugal and viscous forces results in developing streamwise vortices that represent an inherent feature of boundary-layer flows over concave surfaces. This very feature was analyzed to reveal most efficient ways to control such flows. Natural and forced evolution of the vortical structure was studied experimentally and numerically on a basis of the Goertler stability theory and receptivity approach. A gentle and flexible technique to generate and maintain streamwise vortices with a given scale was developed and tested for transitional and turbulent boundary layers. It was realized through the imposed boundary condition in a form of a z-regular surface temperature variation. Generated strictly according to basic flow parameters, the vortices were shown either to stabilize the flow situation (extending a stage of the laminar-turbulent transition) or to intensify mixing processes near a wall depending on their scales and growth rates.