Characterization of the Flow Field of Slender Delta Wings with Trailing Edge Jets Using Volumetric PIV

Abstract

Leading edge vortices (LEV) are routinely used for high angle of attack (AOA) lift augmentation. Shear layer instabilities in the LEV make them prone to breakdown of their coherent structures, a phenomenon known as vortex burst. The resulting loss of lift from LEV burst can cause un-commanded wing-roll. Active flow control techniques like trailing-edge blowing (TEB) have been identified in literature [1-8] that can delay vortex breakdown over the surface of a wing. The flow-field of slender delta wings and the characteristics of the LEV have been experimentally studied using qualitative (flow visualization) and quantitative techniques such as hot wire anemometry (HWA), laser doppler velocimetry (LDV), and particle image velocimetry (PIV). The effect of flow and geometric parameters, active and passive methods to control vortex breakdown (VBD) have been discussed in in the literature. The previous PIV studies of the flow field with LEV have been conducted using two-dimensional or planar (2D2C) PIV, and stereoscopic or three-dimensional (2D3C) PIV. However, these techniques present the challenge of accurately reconstructing the flow field from planar slices taken at various Cr stations at different times to understand the physics of the flow field. This paper provides details of experimental mapping of the flow field over slender delta wings at high angles of attack with trailing edge jets (TEJ) using a volumetric PIV (VPIV) system. The objective of this study is to understand the flow physics of LEV breakdown on slender delta wings with trailing edge jets that simulate thrust vectoring using, VPIV, and considering a variety of parameters such as the trailing edge jet angle, Re, Ur, and α.