Ice Accretion Prediction on Helicopter Rotor Blade in Hover Flight

In the present work, numerical results of ice accretion prediction on the UH-1H helicopter rotor blade with a NACA 0012 airfoil are reported. During the winter of 1982-83, the NASA Lewis Research Center and the US Army conducted a helicopter icing flight test (HIFT) program using a UH-1H aircraft at the Canadian National Research Council spray rig at Uplands Airport, Ottawa, Canada. From several hover icing flight conditions conducted in the HIFT program, a test case is selected to be evaluated with numerical analysis. The computation is performed at an airspeed of 4.6 m/s, ambient temperature of -19.0°C, liquid water content of 0.7 g/m³ and an exposure time of 3 minutes. In order to reproduce the experimental aerodynamic conditions the three-dimensional flow field is numerically computed. Both a two-dimensional and three-dimensional approach is followed to predict the ice shape. In the first phase, two different ice accretion codes are used: the NASA Glenn LEWICE with a Reynolds-averaged Navier Stokes (RANS) solver and the MULTI-ICE code, developed by CIRA. The approach of these solvers to carry out the simulation is similar. The ice accretion simulation is performed by calculating the two-dimensional aerodynamic conditions, the impingement region and the final iced shape for several sections along the span of the rotor, extrapolating the operating conditions from the three-dimensional flow field with a step-by-step technique until the total exposure time is reached. In the second phase, a direct three-dimensional ice accretion computation is carried out using a code developed by CIRA. Comparisons with experimental data are shown.