Reynolds Scaling Effects on Dynamic Stall of VR-7 and VR- 12 Airfoils

摘要

This work presents a comparison study of dynamic stall characteristics between VR-7 and VR-12 airfoils as a function of Reynolds number ranging from 200,000 to 1,000,000 at incompressible Mach number. Dynamic stall experiments on these airfoils were conducted in the Ohio State University 6" × 22" Unsteady Transonic Wind Tunnel, which is a blowdown facility capable of harmonic pitch oscillation at frequencies up to 20 Hz. The effects of Reynolds number and reduced frequency (0.05 and 0.1) are evaluated for both static and dynamic stall performance, based on comparisons of the lift, moment, and surface pressure coefficients. Results show that the VR-12 airfoil outperforms the VR-7 airfoil in terms of the stall angle, the maximum lift coefficient, and the maximum negative pitching moment for both static and dynamic stall under the flow conditions investigated. Reynolds number has a stronger effect on the VR-7 performance compared to the VR-12, showing that airfoil geometry influences the sensitivity towards Reynolds number in dynamic stall.