Matthew C. Homola

Effect of Rime Ice Accretion on Aerodynamic Characteristics of Wind Turbine Blade Profiles

A numerical study of rime ice accretion and resultant flow field characteristics of blade profiles for four different fixed speed, stall controlled wind turbines was performed. Analyses were carried out at Reynolds numbers ranging from of 2.5 × 106 to 5.5 × 106, corresponding to the operational wind speeds and angles of attack ranging from −10 degree to + 20 degree. Numerical analyses showed that an increase in blade profile size reduces the dry rime ice accretion at leading edge, both in terms of local mass and ice thickness. A significant change in the flow behaviour and aerodynamic characteristics is observed, when a comparison is made between plain and iced blade profiles. Results showed an increase in both lift and drag coefficients of wind turbine blade profiles with the leading edge ice.

Turbine Size and Temperature Dependence of Icing on Wind Turbine Blades

The dependence of atmospheric icing on temperature and wind turbine size was studied by performing numerical simulations of ice accumulation on five different wind turbine blade profiles at four different temperatures. The profiles were for 450 kW, 600 kW, 1 MW, 2 MW and 5 MW wind turbines, and the temperatures −10°C, −7.5°C, −5°C and −2.5°C. The simulations indicate that generally atmospheric icing is less severe for larger wind turbines in terms of how much the aerodynamics are disturbed, but the opposite can be true under certain specific conditions. It is indicated that the air temperature range at which the transition between glaze and rime ice occurs is lower for the larger wind turbines.

Relation Between Angle of Attack and Atmospheric Ice Accretion on Large Wind Turbine's Blade

A numerical study of wind turbine blade profiles angle of attack variation on atmospheric ice accretion near the blade tip section was performed. Three dimensional computational fluid dynamics (CFD) based numerical analyses were carried out using NACA 64618 blade profile at five different angles of attack ranging from −5 to +7.5 degrees. Based upon the flow field calculations and the super cooled water droplet collision efficiency, the rate and shape of accreted ice was simulated for both rime and glaze ice conditions. The results show that atmospheric icing is less severe at lower angles of attack, both in terms of local ice mass and relative ice thickness.