Organization of Cylinder Wake Using a Splitter-Plate Active Flow Control

Time Resolved Digital Particle Image Velocimetry (TRDPIV) was used in conjunction with spectral analysis to study the effects of Leading Edge Blowing (LEB) flow control on the near-wake of a circular cylinder. The airfoil was placed 1.9 circular cylinder diameters downstream, effectively acting as a splitter plate. Spectral measurements of the TRDPIV results indicated that the presence of the airfoil decreased the Strouhal number from 0.19 to 0.12 as anticipated. When activated the LEB jet organized the circular cylinder wake, effectively neutralizing the effect of the splitter plate and modifying the wake so as to return the Strouhal number to 0.19. Thus the circular cylinder wake returned to its normal shedding frequency, even in the presence of the airfoil. Evidence presented in this study supports the notion that the LEB jet directly excites the circular cylinder shear layers causing instability, roll up, and subsequent vortex shedding.