AN EXPERIMENTAL INVESTIGATION OF SECONDARY FLOW IN AN ACCELERATING, RECTANGULAR ELBOW WITH 90 deg OF TURNING

Secondary flow tests were conducted on an accelerating elbow with 90 deg. of turning designed for prescribed velocities that eliminate boundary-layer separation by avoiding local decelerations along the walls. Secondary flows were investigated for six boundary-layer thicknesses generated on the plan...

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Bibliographic Details
Main Authors: STANITZ, JOHN D, OSBORN, WALTER M, MIZISIN, JOHN
Format: Report
Language:English
Subjects:
BOUNDARY LAYER
DECELERATION
ENERGY TRANSFER
EXITS
FLOW
FLOW SEPARATION
Fluid Mechanics
INLETS
SECONDARY FLOW
SIZES(DIMENSIONS)
SPOILERS
SUCTION
SURFACES
TEST AND EVALUATION
THICKNESS
VELOCITY
VISCOSITY
VORTICES
WALLS
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Summary:Secondary flow tests were conducted on an accelerating elbow with 90 deg. of turning designed for prescribed velocities that eliminate boundary-layer separation by avoiding local decelerations along the walls. Secondary flows were investigated for six boundary-layer thicknesses generated on the plane walls of the elbow by spoilers upstream of the elbow inlet. The passage vortex associated with secondary flows appears to be near the suction surface and away from the plane wall of the elbow at the exit and does not have appreciable span-wise motion as it moves downstream from the elbow exit. As the spoiler size increases, the boundary-layer form changes and a rather sudden difference in the secondary flow occurs, perhaps associated with the reduced importance of viscous effects in thick boundary layers. It is suggested that the strength of the secondary vortices is small and that the energy of secondary flows is small.