| Straight blade vertical axis wind turbine is a lift type vertical axis wind turbines that attracting widespread international attention in recent years. Straight blade vertical axis wind turbine Suitable for application in the field of small and medium-sized wind energy. Icing on blade of wind turbine will seriously affect the performance of wind turbine, even produce safety accidents. In order to study the straight blade vertical axis wind turbine blade icing features. Especially in the condition of rotating blade icing rule. This study us ing the natural cold climate icing wind tunnel, the static blade of vertical axis wind turbines and rotating rotor model wind tunnel test, and by using numerical simulation of the ice accretion of vertical axis wind turbine aerodynamic characteristics change has carried on the numerical simulation.(1) Vertical axis wind turbine blade static icing characteristics research, mainly adopt the method of wind tunnel test. Adopt natural low temperature freezing test in small icing wind tunnel. Blade airfoil in straight blade vertical axis wind turbine customary NACA0018 airfoil(symmetric) and NACA7715 airfoil(asymmetric). Test is included in the distribution of blade icing test under different attack Angle and blade under zero Angle of attack freezing process te st for a long time. Using high speed camera records freezing process, the use of electronic balance testing quality of ice.(2) Vertical axis wind turbine rotor blades icing characteristic research, mainly adopts the combination of wind tunnel test and numerical simulation method. By adopting NACA0018 airfoil made a straight blade vertical axis wind turbine rotor model, the blade number is 2 blades and 3 two blades, test the rotor under different water flow and blade reduction ratio distribution of the rotor blades is icy. Analyzed the blade icing area, the quality of ice, freezing rate, etc. In addition, after freezing blade shape input, rotate the model and simulation calculation before and after freezing blade, explores the blade aerodynamic characteristi cs changes before and after freezing, the ice power coefficient, torque coefficient changes, the rotation of the model ice rotation model before and after the change of the velocity field and pressure field.In this study under the condition of the main conclusions are as follows:(1) Under the zero Angle of attack NACA0018 airfoil ice will begin with a leading edge gradually to crawl on both sides of the growth. NACA7715 airfoil ice is divided into two parts, one part from the front like crawling growth on both sides, the other part of the trailing edge forward crawling. NACA0018 airfoil ice area rate trend is gradually decline, NACA7715 airfoil ice area trend of speed is increased before they fall. NACA0018 airfoil and NACA7715 airfoil leading edge growth trends are the speed of the ice thickness decreases with the increase of the time. NACA0018 airfoil ice thickness on both sides did not grow, frozen metaphase begins to grow, gradually slow growth to a certain degree of speed. Relatively stable growth NACA 7715 on both sides of the ice thickness. NACA0018 airfoil and NACA7715 airfoil ice effect rate of the overall trend is declining.(2) Under a certain wind speed, blade surface ice are greatly influenced by the Angle of attack changes. When the blade Angle of attack between- 90 ° ~ 10 °, frozen mainly appears in the back of the blade. When the blade Angle of attack from 0 °, frozen mainly appear in the blade leading edge. When the blade between 10 ° ~ 90 ° Angle of attack, frozen mainly appear in the blade in the stomach. The ice in flow is large, low wind speed is greater than the freezing high wind speed as a whole. NACA0018 airfoil ice area than the overall greater than and NACA7715 airfoil ice area ratio.(3) Straight blade vertical axis wind turbine rotor blades, freezing the entire blade surface with static blade icing are quite different. Blade icing condition and the more significant with the increase of LWC, tip speed ratio. Leaf blade icing area ratio increases over time, a certain linear variation law. Under the condition of the same small wind machine single blade icing rate is smaller, the greater the firm for the whole machine, compaction degree, the greater the freezing rate is higher.(4) the numerical calculation results show that the rotating blade freezes reduced lift coefficient, drag coefficient increases, and increased with the increase of tip speed ratio and the amount of ice and the trend of increasing; The power coefficient of wind machine also drops, the tip speed ratio is larger, downward trend is obvious. After freezing blade airfoil pressure field and velocity field around the different degrees of change, make the blade aerodynamic characteristics change.This study can provide vertical axis wind turbine blades of anti-icing and deicing technology provides the experimental basis. |
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