A Research On Aerodynamic Characteristics Of Lift-drag Combined Type Vertical Axis Wind Turbine

In recent years,energy crisis is constantly increasing and the development of renewable energy is paid much attention in the world.Wind power as a kind of renewable energy sources is enormous reserves,widely distributed,clean and low cost.More and more countries and industry attach importance to it.In China,the development of wind power in recent years is very quickly.In 2009,the total installed capacity reached 13803 MW,and China became the second national of wind power industry in the world.Future energy situation will be more conducive to the growth of wind energy,and particularly,in 2011,the first year of " Twelve Five-Year " plan,wind energy has been included in the key developing project,and as domestic manufacturers gradually product,domestic wind power equipment is expected to steadily increase,the development and research fields of wind energy become increasingly forward,so the wind energy-related projects with R & D and technological innovation will increasingly have broad prospects.However,scientists around the world have researched wind turbine for many years,and wind turbine technology has made rapid development,the theory of wind turbine mature,stable species.Under this background,the development of new wind turbine needs new ideas.In this reasearch,a combination method of thinking is used,two complementary performance of wind turbine are used in combination with their respective advantages to develop a new wind turbine.In this study,we try to compose drag-type wind turbine with lift-type wind turbine.The good starting performance of drag-type wind turbine is used to improve the starting characteristics of lift-type wind turbine,and we research the aerodynamic characteristics of the combined type wind turbine by wind tunnel test and computer simulation in order to provide a theoretical basis for research and development of the vertical axis wind turbine.The specific contents and conclusions are as follows.1)Wind resource in the campus of Northeast Agricultural University was measured.The average anural wind speed is 3.09 m/s.Based on the investigation and analysis results,This area belongs to low wind speed region,and it needs to induce the vertical axis wind turbine suitable for low wind speed features.2)A program was made for the design of straight-bladed vertical axis wind turbine(SB-VAWT)by double multiple streamtube theory,and a wind turbine was designed with 1500 W rated power at 12m/s wind speed.And then,a combined type wind turbine(CSB-VAWT)was designed by combining a different phase three stage Savonius rotor to this straight-bladed vertical axis wind turbine.The output power performance was simulated by aerodynamics theories.3)Wind tunnel tests were carried out on both the SB-VAWT and the CSB-VAWT.At low wind speed,the SB-VAWT can not start by itself.On the other hand,the CSB-VAWT had good self-starting performance,and it had good output power performance under high rotation speeds.At high wind speed,the starting performance of CSB-VAWT was also better than the SB-VAWT.However,the power coefficient of CSB-VAWT reduced in some degree compared with the SB-VAWT.By the results of computer simulation on the flow field and pressure field around the two types of wind turbine,the existence of Savonius rotor affected the wind to the blades behind the rotor and thus affected the aerodynamics performance of the blades.As a results,the power performance of CSB-VAWT became poor than the SB-VAWT.Therefore,for the further works of the author is to research the best combination factor for the two types of wind turbine.The combined type wind turbine should both have the good starting performance and good dynamic performance that the Savonius rotor can not affect the performance of SB-VAWT and high rotational speed and can have the function of brake to protect the wind turbine at large wind speed.4)Based on the analysis of wind tunnel tests and computer simulation,there is certain difference between them.Therefore,the program should be further improved to be a good tool for the development and utilization of vertical axis wind turbine.The results of this research can be used as a theatric and experimental reference for the development and utilization of wind energy in low wind speed region,and also for the research of new type of vertical axis wind turbine.