Continous colouhed smoke-wire technique for flow visulisation in wind tunnels

A continuous coloured smoke-wire technique has been developed for flow visualisation in wind tunnels. The improved contrast of coloured smoke sheet facilitates flow visualisation. In the present technique, a vertical smoke-wire is used for introducing controlled sheets of smoke streaklines during a wind tunnel run. Regulated drops13; of a mixture of paraffin oil with coloured 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 coloured droplets along the length.The oil mixture subsequently evaporates through the resistive heating13; of the wire thus producing a sheet of coloured treaklines. The present technique has been used in the NAL 0.9m low speed wind tunnel for flow visualisation around the wing of an aircraft configuration and also a delta wing model at high incidence