Research on ice accretion on an aerofoil and its effect of aerodynamic characteristics of iced aerofoil and blade

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The low temperature wind tunnel tests for ice accretion on a two dimensional aerofoil model were carried out under the appropriate combinations of the parameters which decide the ice shape and properties. Prior to it, the wind tunnel and the droplets emitter were newly designed and built. From the tests the wide variety of ice shapes were acquired. Moreover the growth-rate of ice and the capture ratio were investigated and the several new findings were accordingly obtained. Using some of those results regarding to the ice shape, the two dimensional aerofoil models with ice for the wind tunnel testing were made. The pressure distribution around the iced aerofoil was measured. It turned out that ice accretion at the leading edge affects significantly the pressure distribution around the aerofoil with ice which was developed in particular form and size. The elastic equations for the turbine blade based on the beam theory were developed and numerically solved. The consequence was that the larger ice accretes, the more the blade's natural freqencies change. From the comparison between the rotor revolutions which are closely related to the frequency of the exciting forces and the blade's natural frequencies which increase with the rotor revolutions, it could be resulted that the resonance might occur when the blade be poorly designed in terms of the natural frequencies. The effect of ice accretion on an aerofoil on the aerodynamic characteristics was numerically investigated using the solver for the incompresible viscous flow (Navier-Stokes code). The aerodynamic coefficients were calculated and applied for performance evaluation of the rotor with ice. Ice accretion on the rotor blades affects negatively the rotor performance Therefore the effect of icing should be taken into consideration when the turbine would be situated in icing-endangered areas.