Numerical Simulation of a Pitching Airfoil Under Dynamic Stall of Low Reynolds Number Flow

Mojtaba Honarmand,Behzad Forouzi Feshalami,Mohammad Hassan Djavareshkian,Esmaeil Esmaeilifar

doi:10.5028/jatm.v11.1076

Mojtaba Honarmand, Behzad Forouzi Feshalami + Show 2 more

Open Access

https://doi.org/10.5028/jatm.v11.1076

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Abstract

In this research, viscous, unsteady and turbulent fluid flow is simulated numerically around a pitching NACA0012 airfoil in the dynamic stall area. The Navier-Stokes equations are discretized based on the finite volume method and are solved by the PIMPLE algorithm in the open source software, namely OpenFOAM. The SST k - ω model is used as the turbulence model for Low Reynolds Number flows in the order of 105. A homogenous dynamic mesh is used to reduce cell skewness of mesh to prevent non-physical oscillations in aerodynamic forces unlike previous studies. In this paper, the effects of Reynolds number, reduced frequency, oscillation amplitude and airfoil thickness on aerodynamic force coefficients and dynamic stall delay are investigated. These parameters have a significant impact on the maximum lift, drag, the ratio of aerodynamic forces and the location of dynamic stall. The most important parameters that affect the maximum lift to drag coefficient ratio and cause dynamic stall delaying are airfoil thickness and reduced frequency, respectively.

Highlights

By 2030, energy consumption will be increased more than two-third of present condition worldwide (Dorian et al 2006)
The results showed that each increase in the reduced frequency rapidly enhances aerodynamic characteristics of the oscillating airfoil and decreases the size of vortices formed around the airfoil
The main objective of this paper is to investigate the effects of k, d, Reynolds number (Re) and airfoil thickness on aerodynamic force coefficients and dynamic stall delay to specify the most effective ones on maximum lift to drag coefficient (Cl/d,max) and delay of dynamic stall for 1 × 105 ≤ Re ≤ 2 × 105

Summary

Introduction

By 2030, energy consumption will be increased more than two-third of present condition worldwide (Dorian et al 2006). Dynamic stall can be considered as a delay in separated flow over wings and airfoils due to rapid variation of the angle of attack in the unsteady motion (Carr 1988). Dynamic Stall Phenomenon (DS) can be simulated by various models. Many researchers (Merz et al 2012; Holierhoek et al 2013; Liu et al 2014; Howison and Ekici 2014; Dyachuk et al 2014 Dyachuk and Goude 2015a; 2015b; Antonini et al 2015; Zanon et al 2015; Wang and Zhao 2015; Elgammi and Sant 2016) presented new models to simulate DS, some of them comparing their results with the famous Leishman-Beddoes model.

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