Flow visualization through the use of the smoke-wire technique

A technique for flow visualization in low speed wind tunnels, called the smoke-wire technique, is described. This technique allows for the introduction of very fine smoke streaklines into the flow field. These streaklines are generated through the resistive heating of a very small diameter wire which is coated with oil and which spans the wind tunnel test section upstream of the test object. The description of an electronic control circuit to aid in photography is given. Several practical applications for this technique are demonstrated and streakline data from still photography are presented.