Application of Helium Filled Soap Bubbles and STB for 3D PIV investigations of large-scale passive flow control devices

The paper deals with application of large-scale PIV for investigation of flow field over structured surfaces used for flow control. The aim of the work was to demonstrate the feasibility of Helium Filled Soap Bubbles for investigation of passive flow control in wind tunnel at real-world scale and flow speeds. The flow control strategy relies on creating vortex formations in the boundary layer with use of dimples. To match the Reynolds number representative for automotive and general aviation aerodynamics the measurements were performed in low-speed wind tunnel with test section diameter of 5 m at flow speeds 20, 30 and 40 m·s-1. Application of HFSB enabled for 3D PIV measurements in large volume of 0.5 m3 and revealed change in flow topology over structured surface.