Study On The Aerodynamic Characteristics Of Small Wind Turbine Blade Icing

Recent years, the global total installed capacity of wind power grows exponentially, However, wind farms located in cold regions are tend to face the problem of icing and snow coating, it was these problem that confine the security and reliability of wind farms' operation. Although large quantities of researches related to the law of wind blade's icing and the change of aerodynamic performance after ice accretion have been studied by scholars all over the world, the law of winds' utilization ratio change in the process of blade's ice accretion's studies are rare, and the power character experiment of wind turbine(WT) after ice accretion have not been reported. Therefore, studying the icing's type and severity's influence on blade's wind utilization ratio, performing WT's icing experiment in artificial climate chamber and getting WT's output power character law with ice accretion have both theoretical and practical value to the WT's safe operation in cold regions.This dissertation starts with an introduction of WT's Aerodynamics fundamental theories, basing on the momentum-blade element theory, deducting the expression of wind utilization ratio of ideal WT; then, establishing numerical model of a common airfoil, studying typical glaze and rime's influence on the airfoil's aerodynamic parameters, calculating airfoil wind utilization ratio at different ice severity to obtain its dynamic process considering ice accretion and the change of blade tip speed ratio at the same time; finally, performing small WT's artificial icing experiment to gain the change of output power with ice accretion and comparing with the calculating results to verify. This dissertation's main work and results are list below:(1) Introducing WT ' s Aerodynamics fundamental theories, basing on the Momentum- Blade Element theory, obtaining the direct influence factors of wing utilization ratio, then calculating and analyzing its variation law, providing theory basement to icing's influence on the airfoil wind utilization ratio in the later work.(2) Using hydrodynamic software FLUENT simulating different severity of glaze and rime's influence on common airfoil aerodynamic performance and wind utilization ratio, considering the change of blade tip speed ratio and analyzing the influence of different ice shape and severity to wind utilization ratio. The results show that the wind utilization ratio decrease rapidly at the beginning of glaze and drop slowly with time; what's more, the wind utilization ratios' decrease speed of rime is smaller. It can be concluded from the results that glaze has a more severe influence on wind utilization ratio than rime.(3) Performing icing experiment of small WT in the multi-functional artificial climate chamber, studying WT blade's law of icing distribution and output power with ice accretion at different environmental parameters. Studies show that small WT blade icing located at blade's lead and windward side, and has the shape of horned protuberance at the lead, leading to dramatic drop of WT's output power; different environmental parameters will influence the decent speed of WT's output power.(4) Through comparative analysis of calculation and experiment results, both results have the same trend. At the beginning of icing, the blade's aerodynamic performance deteriorates rapidly, the wind utilization ratio and output power drop dramatically; with the glaze growing, the drop trend getting slowly and becoming steady.