Exploration of turbulent separation over a CRM-HS model in a large scale wind tunnel

Abstract

The turbulent separated flow on a 4% High-Speed Common Research model (CRM- HS) configuration was studied using particle image velocimetry (PIV) in Kirsten Wind Tunnel (KWT) at the University of Washington without the nacelle/pylon group. The experiments were conducted for a range of Reynolds numbers and Angles of Attack (AOA) using tuft flow visualization to determine test conditions for PIV. The data is acquired in two configurations, namely side-on PIV and top-down PIV. In the side-on PIV, data is acquired in two fields of view (FoV) at three Reynolds numbers (Re = 5 ⇥ 105, 106, and 1.48 ⇥ 106) and three angles of attack (AoA) 10.5, 12, and 13.5 to explore the sensitivity of the separation region. In top-down PIV, data was acquired at two Reynolds numbers and one angle of attack (AoA) to explore the separation region along the wing span. A nominal case was set to a Reynolds number (Re) = 106 at AOA 12. The separated flow in the nominal case didn’t show reattachments on the wing surface. The boundary layer thickness increased with increasing angles at Re = (106), while the boundary layer thickness decreased with increasing Reynolds number at angle 12. In top-down orientation, the flow is reversed near the wing surface in the streamwise direction and moves from root to tip in the spanwise direction. This experiment is the first step in designing the required hardware for the laser, camera mounts, and slides to enable PIV tests in a big-scale Kirsten wind tunnel facility. It also plays a key role in many upcoming tests on a more complex CRM-HL wing geometry to acquire high-quality experimental data for CFD validation studies.