Research on Bluff-Body Vortex Wakes
CALIFORNIA INST OF TECH PASADENA GRADUATE AERONAUTICAL LABS
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A computational technique, based on two dimensional vortex methods, was developed to study unsteady flows past flat plates with large-scale separation and in the RE range of 10,000. The technique captures the actual scale of the vortex sheets as they emerge from the edges of the plate. This scale defines the flow Reynolds number. The accuracy of the method was verified by comparison with tow-tanks measurements of time-dependent drag during a ramp start, comparison with theoretical results of Pullin on the time-dependent vortex circulation after an impulsive start, and comparison with experiment of the growth of the recirculation bubble before flow asymmetry begins. Nonoscillating Case, Oscillating Cases plate oscillating in its place, Wake- Interference Effects. An experiment has been initiated in our 20 X 20 in. wind tunnel. Behind circular cylinders or the bluff cylinders spanning the tunnel, solid splitter plates or screens open splitter plates can be installed. Preliminary measurements show the expected effect of the screen splitter, ie reduction of drag but not so much as for a solid splitter. Variations with Reynolds number observed.
- Fluid Mechanics