Large eddy simulation of transitional separated flow over a low Reynolds number cambered airfoil
Loading...
Date
2023-03
Authors
Zilstra, Alison
Johnson, David A.
Journal Title
Journal ISSN
Volume Title
Publisher
American Society of Mechanical Engineers
Abstract
The accurate simulation of the aerodynamic behavior of low Reynolds number (Re) cambered airfoils requires the ability to capture the transitional separated boundary layer (BL) that occurs naturally on the surface of the airfoil. In this study, simulations are performed using a modern cambered airfoil designed for use in low Re applications, which are an advancement from previous studies using flat plate geometries or symmetric NACA airfoils. The cambered SD 7037 airfoil is simulated using wall-resolved large eddy simulation (LES) at a modest Re of 4.1×10⁴ and at 1 deg, 5 deg, and 7 deg angles of attack (AOAs), with results validated against experimental data. Simulated predictions of pressure and skin friction coefficients clearly capture the correct location of the laminar separated bubble (LSB) which forms during the natural BL transition process. Sensitivity to elevated inflow turbulence is found to cause early BL reattachment at higher AOAs without impacting the location of BL separation. An integral BL analysis verifies the accuracy of the simulated velocity profiles against experimental values. The scale of horseshoe structures visualized in the transitional BL is larger in comparison to airfoil chord length than what is seen in previous simulations at Re of the order of 10⁵, which highlights the importance of investigating cambered airfoils at a modest Re.
Description
Published by the ASME
Keywords
computational fluid dynamics, large eddy simulation, low Reynolds number, transitional separated flow, cambered airfoil, laminar separation bubble