Effects of Channel Rotation on Turbulent Boundary Layers along a Convex Surface.

Effects of the centrifugal force due to wall curvature and the Coriolis force due to system rotation on turbulent boundary layers along a convex surface are studied experimentally using a curved channel of a constant cross-section rotating about an axis perpendicular to the main flow. Time-averaged and turbulent components of the velocities inside the channel were measured using hot wire probes during the channel rotation. Besides wall curvature, channel rotation was found to have a large effect on stabilization or destabilization of the turbulent motion in the boundary layer. Stabilizing effects appear more dominant on the suction side, and the flow tends to become laminarized there. When the Coriolis force acts toward the convex surface resulting in higher pressure on that side, the destabilizing effects due to the force cancel the stabilizing effects of the centrifugal force, and the velocity profiles are almost unchanged in the downstream direction. Comparison was made with the turbulence behavior on the concave surface in the same channel

An experimental study on axial flow pump operated as a turbine model with draft tube

An experimental investigation concerning the analysis of system performance for axial flow pump operated as a turbine with draft tube is presented. The dimensional analysis is used to derive the functional relationship between discharge coefficient and energy coefficient. The two parameters and the one-dimensional flow theory are found useful to establish the turbine performance diagram. In this study, the Reynolds number in the upstream part of an axial flow turbine model is ranging from 90,000 to 170,000. © 31st IAHR Congress 2005: Water Engineering for the Future, Choices and Challenges. All Rights Reserved