Continuous coloured smoke-wire technique for flow visualisation

Abstract

A continuous colored smoke-wire technique has been developed for flow visualization in wind tunnels. The improved contrast of colored smoke sheet facilitates flow visualization. In the present technique, a vertical smoke-wire is used for introducing controlled sheets of smoke streaklines during a wind tunnel run. Regulated drops of a mixture of paraffin oil with colored dye are allowed to fall along the stainless steel wire. The wire is thus coated with a thin film of falling paraffin or with minute colored droplets along the length. The oil mixture subsequently evaporates through the resistive heating of the wire thus producing a sheet of colored streaklines. The present technique has been used in the NAL 0.9m low speed wind tunnel for flow visualization around the wing of an aircraft configuration and also a delta wing model at high incidence.