RANS Simulations of Airfoils with Ice Shapes

Abstract

Numerical simulations were conducte d to investigate the effect of simulated ridg e ice shapes and leading -edge ice shapes on the aerodynamic performance of airfoils and wings . A range of Reynolds number s and Mach number s, as well as ice -shape size s and ice -shape location s were examined for t he NACA 23012 airfoil, the NLF 0414 airfoil and the NACA 3415 airfoil. The results were compared to experiments completed recently at the NASA Langley Low Turbulence Pressure Tunnel (LTPT) and the University of Illinois Low -Speed Wind Tunnel . Additionally, the LTHS (Large Transport Horizontal Stabilizer) airfoil , the BJMW (Business Jet Main Wing) airfoil, and a tape re d NACA 23012 wing were also studi ed to investigate ice -shape location effect with various airfoil s and wing geometries . The RANS investigation included steady -state simulations with the Spalart - Allmaras turbulence model and a structured grid. Comparisons with experimental force data showed favorable comparison up to (but not including) the stall conditions , with improved fidelity for forward and smaller ice shapes . At and past stall condition, strong separation occurs and the aerodynamic forces are not predicted accurately for large upper -surface ice shape s due to the limitation of RANS method. A lift -break (pseudo -stall ) condition was defined ba sed on the lift curve sl ope change. The lift -break data compared well with experimental stall results , and indicated that the upper surface critical ice -shape location tended to be near (and often in between) the location of minimum pressure and the locati on of the most adverse pressure gradient .