Near-wake measurements of a delta wing in a supersonic stream

The near-wake region of a 75-deg sweptback delta wing was studied experimentally in a Mach 2.49 stream. Five-hole conical probe measurements were conducted vertically and horizontally through the primary vortices at the trailing edge and half-chord downstream of the planform for 7- and 12-deg angles of attack. The Mach number and pressure distribution profiles are summarized, and comparisons of flow properties at different survey stations are presented. A novel calibration approach using a three-dimensional Navier-Stokes solver to generate numerically the calibration data for a blunt-nosed five-hole conical probe over a range of Mach numbers and pitch angles was employed. The magnitude of the pitot, total, and static pressure deficits in the wake region increased with increasing angle of attack for the same measurement plane and decreased with the downstream distance. The swirl profiles have supersonic and high transonic peak magnitudes, and estimated core dimensions suggest vortex stretching in the vertical direction and convection downstream. A decrease in the radial Mach number component confirms the vortex trajectory changes from a strong downward flow over the planform to a gradual return toward the freestream in the near wake. Unlike the experimental results from transonic and low-speed leading-edge vortices, the axial and total Mach number distributions in supersonic vortices are found to be wakelike.