A new technique for introducing controlled sheets of smoke streaklines in wind tunnels
Abstract
A new flow visualization technique utilizing a vertically oriented 'smoke wire' for introducing controlled sheets of smoke streaklines has been developed for use in wind tunnels. The 'smoke wire', mounted on a portable probe, is a 0.1 mm. diameter wire onto which regulated drops of oil are allowed to fall, coating the wire in the form of minute droplets along its length. The oil is subsequently burned off through the resistive heating of the wire resulting in droplet produced, discrete streaklines. A synchronization circuit, which is activated by energizing the wire, controls the duration of time the wire is supplied with the heating current and triggers the camera and strobe lights after an adjustable time delay. Thus, only small amounts of smoke are required to obtain quality photographs, thereby reducing the contamination of the flow in recirculating wind tunnels caused by the accumulation of smoke. The 'vertical smoke wire technique' has been used to study various complicated flowfields around bluff bodies and in boundary layers for velocities up to 6 m/sec. and turbulence intensities as high as 12 percent.
- Publication:
-
ICIASF 1977; 7th International Congress on Instrumentation in Aerospace Simulation Facilities
- Pub Date:
- 1977
- Bibcode:
- 1977icia.cong...74C
- Keywords:
-
- Flow Visualization;
- Smoke Trails;
- Streak Photography;
- Vortex Sheets;
- Wind Tunnel Tests;
- Electronic Control;
- Flow Distribution;
- Low Speed Wind Tunnels;
- Probes;
- Systems Analysis;
- Instrumentation and Photography