Development of Two-Color PIV for Large-Scale Wind Tunnel Facility
Abstract
A two-color PIV technique was implemented in an open circuit, low speed wind tunnel which has a 3.05m x 2.13m test section. A sharp leading edge delta wing model with and without twin vertical tails was chosen for the test runs. The tails were located along a radial line emanating from the apex of the delta wing along a constant 64.3 percent span location. The model was tested at 23-deg. angle of attack, a Mach number of 0.2, and a Reynolds number of 1.87 x 106 (based on root chord). At this condition, no vortex bursting was present over the model surface on the clean delta wing. However, the presence of the tails caused the vortices to burst near the mid-chord location. Furthermore, the bursting was unsteady and a considerable oscillation was observed in the burst location. Several PIV implementation issues such as seeding concentration, laser-sheet illumination, and image recording optics were explored. Smoke particles were introduced into the flow for seeding. Two frequency-doubled Nd:YAG lasers were used (one for green and the other for red) for illuminating the particles. Double-exposed two-color PIV images were acquired at four different locations (both in-front and behind the trailing edge of the model) using 35mm and large-format color photographic films and a high-resolution digital color camera. These color mages were processed using cross-correlation technique and obtained the instantaneous velocity and vorticity distributions. An attempt was also made to compare the results with the CFD solution.
- Publication:
-
APS Division of Fluid Dynamics Meeting Abstracts
- Pub Date:
- November 1998
- Bibcode:
- 1998APS..DFD..AC06G