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Spanwise Rotation and Wall Curvature Effects on Instability of Boundary Layer

Koji Kikuyama
Department of Mechanical Engineering, Nagoya University Chikusa-ku, Nagoya Japan 464 4703

Yutaka Hasegawa
Research Center for Advanced Energy Conversion, Nagoya University Furo-cho, Chikusa-ku, Nagoya 464-8603; Department of Mechanical Engineering Nagaoka University of Technology, Nagaoka, Niigata 940-2133, Japan

Noboru Matsumoto
Department of Mechanical Engineering, Nagoya University Chikusa-ku, Nagoya Japan 464 4703

Michio Nishikawa
Department of Mechanical Engineering, Nagoya University Chikusa-ku, Nagoya Japan 464 4703

Abstract

The behavior of the boundary layer flows in rotating channels such as impeller passages of turbomachinery are dominated by the centrifugal and Coriolis forces due to the wall curvature and system rotation, respectively, which predominate the boundary layer development by suppressing or promoting the turbulent motion. Though many studies have been made about the turbulent boundary layer over a concave or convex surface in the stationary state, the resultant effects due to the Coriolis force in the rotational frame of reference have scarcely been researched.
In the present study the velocity and turbulent intensity are measured near the concave surface in channels whose radii of center line curvature are 1,000mm and 2,000mm, respectively, on the rotating system.
When the channel rotates in such direction as the Coriolis force acts toward the wall, the transition of the boundary layer to the turbulent state is promoted because the Gortler instability is enhanced but it is suppressed when the force acts in the opposite direction.