Dynamic Reattachment on a Downward Pitching Finite Wing

A finite wing was pitched downward at a constant rate from a fully stalled condition to zero angle of attack. Dynamic reattachment on the downward pitching wing was characterized in detail using unsteady surface pressure measurements. Results showed that dynamic reattachment initiation and progression velocity varied in response to alterations in nondimensiona l pitch rate and span location. In addition, these alterations to reattachment initiation and progression were prominently reflected in normal force data. An empirical model for dynamically separating flowfields was successfully adapted to account for these observed trends. Comparisons between dynamically reattaching and dynamically separating flows were also informative. Characterization and comprehension of three-dimensional dynamic reattachment are crucial prerequisites for control of unsteady separated flowfields generated by rapidly maneuvering aircraft, helicopter rotor blades, and wind energy machines.

[1]  M. S. Chandrasekhara,et al.  Reattachment studies of an oscillating airfoil dynamic stall flowfield , 1991 .

[2]  A. Panaras,et al.  Numerical Modeling of the Vortex/Airfoil Interaction , 1987 .

[3]  L. Carr.  Progress in analysis and prediction of dynamic stall , 1988 .

[4]  M. Robinson,et al.  Visualization of three-dimensional forced unsteady separated flow , 1986 .

[5]  William E. Faller,et al.  Real-time prediction and control of three-dimensional unsteady separated flow fields using neural networks , 1994 .

[6]  Michael Robinson,et al.  Unsteady surface pressure measurements on a pitching rectangular wing , 1988 .

[7]  William E. Faller,et al.  Real-time prediction of three-dimensional dynamic reattachment using neural networks , 1994 .

[8]  Peter Freymuth.  Three-dimensional vortex systems of finite wings , 1988 .

[9]  William E. Faller,et al.  Neural network prediction of three-dimensional unsteady separated flowfields , 1993 .

[10]  Peter Freymuth.  Physical vortex visualization as a reference for computer simulation , 1991 .

[11]  S. Schreck,et al.  Unsteady vortex dynamics and surface pressure topologies on a finite pitching wing , 1994 .

[12]  Peter Lorber,et al.  Tip vortex, stall vortex, and separation observations on pitching three-dimensional wings , 1993 .

[13]  John E. Burkhalter,et al.  Downwash Measurements on a Pitching Canard - Wing Configuration , 1993 .

[14]  M. S. Chandrasekhara,et al.  Reattachment studies of an oscillating airfoil dynamic stall flowfield , 1994 .

[15]  Ding Lee,et al.  Three-Dimensional Effects , 1995 .

[16]  Mohamed Gad-el-Hak,et al.  Three-dimensional effects on a pitching lifting surface , 1985 .