Assessment of Transitional Model for Prediction of Aerodynamic Performance of Airfoils at Low Reynolds Number Flow Regime 2013-01-2314

There has been an increased interest in low speed aerodynamics for Unmanned Aerial Vehicles (UAVs) and Micro Aerial Vehicles (MAVs). These vehicles which are increasingly being used for reconnaissance purposes operate in the Root Chord Reynolds number range of 10⁴ to around 10⁵ and thus, the flow regime encountered is in the low Reynolds number transitional flow range. Computational Fluid Dynamics (CFD) methods which employ eddy viscosity based RANS turbulence models that are formulated for high Reynolds number flow are not well suited for such low Reynolds number range as they cannot accurately model the formation of laminar separation bubble and subsequent onset of transition.

In this paper, the transition k-ω SST model is assessed for aerodynamics prediction for the SD7003 airfoil for Reynolds number ranging from 10⁴ to 9 × 10⁴ and angle of attack ranging from 0° to 8°. The assessment is carried out against available experimental and Large Eddy Simulation results. The assessment shows that the transition k-ω SST model is able to predict the pressure, lift, and drag coefficients reasonably well over the range of Reynolds number and angle of attack studied in this paper. The predictions of separation, transition, and re-attachment length compare reasonably well with previous documented results; however, at large values of angle of attack the model predict a shorter reattachment length as compared to the Large Eddy Simulation results.