Comparative Study of Numerical and Experimental Aerodynamic Performance of NACA4412 Wind Turbine Airfoil Blade Section Under Atmospheric Icing Conditions

Abstract

Ibrahim Kipngeno Rotich and Ronald Okoth

Wind energy is an emerging renewable energy but its reliability in cold regions is significantly affected by atmospheric icing. Ice accretion alters airfoil profiles by reducing energy production and increasing operational risks and maintenance costs. This study focused on the prediction of aerodynamic performance of iced airfoil blade sections through numerical approach using ANSYS Fluent and FENSAP ICE. The results obtained were verified with the experimental studies in a closed loop wind tunnel that was equipped to replicate the conditions for in-cloud icing phenomena.

The ice accretion was numerically simulated with the aid of FENSAP ICE on NACA4412 airfoil at given conditions such as Liquid water content (LWC) of 0.8 g/m3 , 1.6 g/m3 , and 4.9 g/m3 , angle of attack of α=0 ° to 15 ° , and median volume diameter (MVD) of 50 μm, 51 μm and 54 μm. Temperatures of -4° C and -17° C were considered during the experimental set up and numerical calculations to correspond to the in-cloud temperatures for glaze and rime ice occurrence during Icing. The experimental findings were done in an icing wind tunnel using NACA4412 airfoil blade section during which the LWC, angle of attack and ambient temperature were varied while maintaining the velocity constant at 20m/s. The experimental aerodynamic performance findings showed similar trends with numerical findings. It was observed that an increase in LWC and angle of attack with decrease in temperature led to an increase in ice mass accreted on the airfoil section. The ice shapes were found to be nearly the same for both the numerical and experimental set ups. In both cases, aerodynamic performance was found to decrease gradually with increase in LWC, angle of attack and ice accretion time.

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