Upstream History Effects in High-Reynolds Number Adverse-Pressure Gradient Turbulent Boundary Layers*

Turbulent boundary layers (TBLs) exposed to adverse-pressure gradients (APGs) are encountered in a number of engineering applications such as flows around wings or inside diffusers. Previous studies have demonstrated that the primary parameters influencing the characteristics of these TBLs are the Reynolds number, APG strength, and upstream pressure gradient (PG) history. Furthermore, every experimental investigation of an APG TBL is associated with a unique PG history, resulting from the use of different ramp geometries for example, which can potentially bias conclusions about APG TBL scaling characteristics. As such, past studies have investigated these PG history specific effects, however they have generally been limited to low-Reynolds number TBLs. We now propose to experimentally investigate high-Reynolds number, moderate APG TBLs, developing with variable upstream PG histories imposed using a purpose modified experimental facility. Preliminary results reveal PG history related effects on APG TBL scaling which are comparable to those seen in previous studies at lower Reynolds numbers. These new results additionally allow for comment on the regions of the TBL, and range of turbulent scales, specific to high-Reynolds number TBLs, which are influenced by PG history.