AN EVALUATION OF THE SMOKE-WIRE TECHNIQUE FOR MEASURING VELOCITIES IN AIR
MISSISSIPPI STATE UNIV MISSISSIPPI STATE DEPT OF AEROPHYSICS
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In the smoke-wire technique, oil is evaporated from a very thin, high-resistance wire by the passage of a large electric current through the wire from a capacitor. The resulting line of smoke is carried downstream with the local velocity of the air, deforming so that a photograph of the smoke line after a measured time delay provides a velocity profile. Since the time delay is very short, this velocity profile is very close to the actual velocity profile at the location of the wire. The technique was evaluated in two- and three-dimensional air flows, both laminar and turbulent, by comparisons with theoretical profiles. Experimental velocity profiles compared quite favorably with theoretical solutions for several different types of flows, including boundary layers, jets, wakes, and vortices. Modifications of the technique and associated apparatus were made in order to extend its scope of application.
- Fluid Mechanics