Vortex shedding from a hydrofoil at high Reynolds number

High Reynolds number (Re) wall-bounded turbulent flows occur in many hydro- and aerodynamic applications. However, the limited amount of high-Re experimental data has hampered the development and validation of scaling laws and modelling techni-ques applicable to such flows. This paper presents measurements of the turbulent flow near the trailing edge of a two-dimensional lifting surface at chord-based Reynolds numbers, ReC, typical of heavy-lift aircraft wings and full-scale ship propellers. The experiments were conducted in the William B. Morgan Large Cavitation Channel at flow speeds from 0.50 to 18.3m s−1 with a cambered hydrofoil having a 3.05m span and a 2.13m chord that generated 60 metric tons of lift at the highest flow speed, ReC ≈ 50 × 106. Flow-field measurements concentrated on the foil’s near wake and include results from trailing edges having terminating bevel angles of 44 ◦ and 56◦. Although generic turbulent boundary layer and wake characteristics were found at any fixed ReC in the trailing-edge region, the variable strength of near-wake vortex shedding caused the flow-field fluctuations to be Reynolds-number and trailing-edge-geometry dependent. In the current experiments, vortex-shedding strength peaked at ReC =4 × 106 with the 56 ◦ bevel-angle trailing edge. A dimensionless scaling for this phenomenon constructed from the free-stream speed, the wake thickness, and an average suction-side shear-layer vorticity at the trailing edge collapses the vortex-shedding strength measurements for 1.4 × 106ReC 50 × 106 from both trailing edges and from prior measurements on two-dimensional struts at ReC ∼ 2 × 106 with asymmetrical trailing edges. 1