Campus Units

Aerospace Engineering

Document Type

Conference Proceeding

Conference

23rd AIAA Computational Fluid Dynamics Conference

Publication Version

Published Version

Publication Date

2017

Journal or Book Title

23rd AIAA Computational Fluid Dynamics Conference

First Page

2017-3957

DOI

10.2514/6.2017-3957

Conference Title

23rd AIAA Computational Fluid Dynamics Conference

Conference Date

June 5-9, 2017

City

Denver, CO

Abstract

Large eddy simulations are used to investigate the effects of airfoil geometry, particularly thickness, on inception of dynamic stall. The investigation is performed for three airfoils from the NACA family at Rec = 2 x 105. Three symmetric airfoils are studied with thickness-to-chord ratios of 9%, 12%, and 15%. A constant-rate pitch-up motion about the airfoil quarter-chord point is used to study dynamic stall. A static simulation is first carried out with each airfoil set at alpha = 4 degrees. Results of the static simulations are compared with XFOIL predictions as a sanity check. Good code-to-code agreement is observed for aerodynamic pressure- and skin friction coefficient distributions. A ramp function is used to smoothly increase the pitch rate from zero to the desired value and then held fixed. Dynamic simulations are carried out until the angle of attack goes past the lift stall point. Unsteady aerodynamic loads are compared with the corresponding static values. In all cases, dynamic stall onset occurs immediately following the bursting of the laminar separation bubble. However, investigation of the reverse flow region on the suction surface shows tremendous differences between the different airfoils, with the thickest airfoil showing a very large reverse flow region. These observations suggests that the mechanism of stall onset can change from 'LSB burst' to trailing edge separation as airfoil thickness is further increased.

Comments

This proceeding is published as Sharma, Anupam and Miguel R. Visbal. "Airfoil Thickness Effects on Dynamic Stall Onset", 23rd AIAA Computational Fluid Dynamics Conference, AIAA AVIATION Forum, (AIAA 2017-3957). (2017). DOI: 10.2514/6.2017-3957.

Rights

Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.

Language

en

File Format

application/pdf

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