Simulation numerique et experimentale de l'ecoulement d'air de l'accretion de glace autour d'une pale d'eolienne.

摘要

The wind-energy market is in full growth in Quebec, but technical difficulties due to cold climate conditions have occurred for most of the existing projects. One of the main issues associated with wind energy in cold climates is the icing of the wind-turbine blades. Because meteorological conditions and wind turbines characteristics are different from a place to another, experimental measures in specific places will never be enough and analytical studies using numerical simulations have become essential.; Thus, a numerical model of the air flow around a rotor blade has been developed. This numerical model constitutes the first one of the four modules (Flow, Trajectories, Thermodynamic and Geometry) of the LIMAIcing2D software, developed by Anti-Icing Materials International Laboratory (AMIL) and specifically adapted to simulate the icing of wind turbines. The air flow numerical model runs with a 2D clean or iced blade profile and is made up with 2 different parts: potential flow calculation with the Hess and Smith panel method and viscous boundary layer calculation with Thwaites and Head integral methods.; Experimental measures using an aerodynamic balance have then been carried out in the AMIL wind tunnel on a NACA 63415 wind turbine blade profile in order to build lift and drag coefficients vs attack angle curves. Velocity field has also been measured all around the rotor blade profile with hot wire probes anemometers. Tangential speeds and boundary layer thicknesses have been evaluated by analysing speed measures very close to the blade surface.; Numerical model results, experimental results and literature data have then been confronted in order to validate the air flow numerical model. For clean blade profiles and when Reynolds number is high enough (Re > 4.0*10 6), the results of the numerical model are validated for positions before the stall region and for attack angles between 0° and 15°. For iced blade profiles, results concerning tangential speeds and boundary layer parameters are not so good but, results concerning velocity fields and stream lines, which are not parameters directly linked to the blade profile surface, look to be coherent for positions in front of big ice deposits.; Icing simulation was finally carried out on the NACA 63415 blade profile in the AMIL refrigerated wind tunnel. The shapes and masses of the ice deposits were measured as well as the aerodynamic lift and drag of the iced blade profiles. The conditions for simulation in the wind tunnel were based on meteorological data measured at the Murdochville wind farm in the Gaspe Peninsula during in-fog icing. Two different in-fog icing conditions were considered, characterized by wind speed of 8.8 and 4.4 m/s, respectively, generating wet and dry ice accretions. Scaling was carried out based on the 1.8 MW - Vestas V80 wind turbine technical data, for three different radial positions and two in-fog icing conditions. In wet regime testing, glaze formed mostly near the leading edge and on the lower surface. It accumulated by runoff on the trailing edge for blade profiles located at the centre and tip blade. In dry-regime testing, rime accreted on the leading edge and partially on the lower surface of the blade profiles located between the middle and the tip blade. In both dry and wet regimes; because of a greater ice amount for high radial positions, lift decreased with an increase in radial position, while drag increased following a power law. Between the centre and the tip, drag increased considerably compared to lift, which seriously decreased rotor blade aerodynamic performances. An ideal horizontal-axis wind-turbine model was finally used to evaluate the impact of the lift reduction and drag increase on the wind turbine blade. For both icing events, the model shows that drag force becomes too great compared to lift, resulting in negative torque and the wind turbine stoppage. Torque reduction is more significant on the last half of the bla