On the Informed Flow Control Over a Blended-Wing-Body Model and its Simple Surrogate of Identical Planform

Tests were carried out in a university-scale atmospheric wind tunnel on a NATO designed Swept Wing Flow Test (SWiFT) model at incompressible Mach numbers and Reynolds numbers (Re) ranging from Re=0.2 x 10⁶to Re= 2 x 10⁶. The initial purpose was to compare results with those from the National Transonic Facility (NTF) to assess the significance of Re. After comparing the force balance data of the two tests and seeing that an increase in Re did not result in novel phenomena, the evolution of the Leading-Edge Vortex (LEV) and its lift-off from the surface due to the LE crank was investigated. Based on this information, a single small jet was chosen to alter the forces and moments acting on this model and provide information about the interaction between the small jet and the LEV. Preliminary results indicate that the location and orientation of a jet actuator are as important as the jet momentum, therefore requiring optimization for different parts of the flight envelope. To ascertain the significance of the crank angle and its location on the wing relative to other design parameters, a simplified flat-top lambda wing planform with a sharp leading edge was tested at Re= 1.2 x 10⁶. Oil flow visualization exposed the differences between these two models that were exposed by probing the LEV by Particle Image Velocimetry (PIV). The use of PIV revealed extremely large periodic oscillations in the flow that were associated with localized separation and vortex lift-off, providing a reason for flutter. These oscillations were observed on both models, and they were attributed mostly to the crank. Consequently, a substantial reduction of these oscillations became an added task for the useful application of Active Flow Control (AFC).