Abstract : An investigate study of the three-dimensional, unsteady flow field about a sinusoidally pitching forward swept wing, straight wing and aft swept wing was conducted. The flow field was documented using a smoke wire technique and stroboscopic photography. Photographs were taken from both side and top view perspectives at span locations from wingtip to 1.33c inboard. A comparative study between these wings is made with the smoke sheet at identical span locations for each. The unsteady flow field was produced by sinusoidally oscillating the wings about the quarter chord between angles of attack of 5 and 25 deg at reduced frequencies of 0.0, 0.6, 1.0, and 1.4. Static stall characteristics seem to directly influence the dynamic vortical structure formation, growth and traversing tendencies. The interactive effects between dynamic wingtip and leading edge vortex size and location show effects of wing sweep and reduced frequency. Multiple vortex formation during the initial phase of the pitching cycle and leading edge vortex splitting were observed. Keywords: Flow visualization; Pitch motion; Sweptback wings; Three dimensional flow; Sweptforward wings.
[1]
Mohamed Gad-el-Hak,et al.
Three-dimensional effects on a pitching lifting surface
,
1985
.
[2]
M. Robinson,et al.
Visualization of three-dimensional forced unsteady separated flow
,
1986
.
[3]
Hank E. Helin,et al.
Interrelated Effects of Pitch Rate and Pivot Point on Airfoil Dynamic Stall
,
1985
.
[4]
D. Frei,et al.
X-29 forward swept wing aerodynamic overview
,
1983
.
[5]
M. Luttges,et al.
Three-dimensionality in unsteady flow about a wing
,
1985
.
[6]
Chih-Ming Ho,et al.
Unsteady vortical flow around three-dimensional lifting surfaces
,
1986
.
[7]
M. Luttges,et al.
Unsteady Separated Flow. Forced and Common Vorticity about Oscillating Airfoils
,
1984
.
[8]
Visualization of Wing Tip Vortices in Unsteady and Steady Wind
,
1986
.
[9]
L. W. Carr,et al.
Water Tunnel Visualizations of Dynamic Stall
,
1979
.