COMPARISON OF RESULTS OF RANS AND ILES BASED CALCULATIONS FOR A THICK TEARDROP AIRFOIL AT LOW REYNOLDS NUMBERS

Abstract

A flow around a symmetrical thick teardrop airfoil in a nonstationary formulation is numerically modeled at Reynolds numbers \(\mathrm{Re}=10^4{-}10^5\) and in a range of angles of attack \(\alpha=~-10{-}10^\circ\). Calculations are based on the approximation of unsteady Reynolds-averaged Navier–Stokes (URANS) equations using the implicit large-eddy simulation (ILES). The URANS approach requires that the position of a laminar-turbulent transition is determined using \(k{-}kl{-}\omega\) and \(k{-}\omega{-}\gamma{-}\mathrm{Re}_\theta\) models, as well as (\(k{-}\omega\))-SST models with a given laminar flow region. It is shown that the flow pattern and aerodynamic characteristics of the airfoil are greatly affected by the position of the laminar-turbulent transition region. It is suggested by the comparison of the results obtained using the ILES approach with experimental data that they are in good agreement. The URANS based calculations do not yield results consistent with experimental data. Fixing the laminar-turbulent transition point in the URANS calculation in some cases make it possible to correct the results.