| With the energy crisis intensifies and people’s increasing awareness of environmental protection, wind energy as one of the clean, non-polluting and renewable energy sources, has attracted world high attentions. Wind energy utilization in the building environment has the advantage that it can avoid transporting, which can greatly solve the power supply of remote region; especially it has important significance for residents without electricity. Taking wind energy utilization around the building environment as starting point, this paper mainly analyzes the basic situation of three-dimensional wind field around the buildings using the method of the theoretical analysis and CFD numerical simulation. In this paper, the variation situation of wind speed and turbulence intensity at the roof of building along with the change of heights can be discussed, which can provide theoretical support for installing wind turbines at building roof.Firstly, this paper adopted CFD numerical simulation to analyze the wind fields of single flat-top building, single spire-top building and two adjacent flat buildings, and discussed the wind turbine installed suitable heights at different type roofs of buildings considering wind speed and turbulence intensity. The consequences indicate: different type roofs buildings have gather effects for wind energy, and the wind velocity above roof can increase more than 20%, which can get more wind energy for wind turbine. The turbulence intensity can become increased because of the disorder of wind when the wind flows through the building, and the turbulence intensity is highest at the middle area of building roof. Contrast flat-top building and spire-top building, the wind field can be effected enormously by the different type roofs, and the suitable heights installing wind turbines are different. For two adjacent buildings, because of the block of the front building, the wind speed of the back building can be decreased, and then the suitable heights installing wind turbines are increased. In addition, through simulated wind field around different height buildings, the heights installing wind turbines at roof can become increased along with the increasing of building height; the installing height at building roof is generally not less than 1/3 of the building height for the flat-top building.Secondly, this paper analyses the single flat-top wind field under the condition of the building roof installed wind turbines according to the simulation results of the wind field around building without installing wind turbine. And considering the influence of turbines’ wakes, the compositions and heights installing wind turbines at building roof can be further discussed. The analysis shows that, wind turbines’ wakes have a great influence of wind field on the roof of building, which can directly influence the installed positions and heights of wind turbines. According to the analysis of wind field of the single flat-top building roof which installed wind turbines, and combined the features of wind field and turbines’ wakes, the wind turbines installed positions of single flat-top building can be showed. Soduring the actual installation it is necessary to consider the influence of wind turbines’ wakes, and rational distribute the installed positions of turbines within the limited roof space to realize the maximization use of wind energy.Finally, the paper designed a kind of spiral vertical axis wind turbines whose rated power is 300 w to apply to building roof according to the use of wind energy around buildings, and determined the size of the wind turbine parameters. In order to study the actual performance of the spiral type wind power generator, blowing tests have been carried out. This paper focuses on the experimental scheme and test device, conducts tests about the blade installation angle, different blade installation angle and stents, and gets the test results. Through comparison and analysis, it can determine that the design of spiral wind turbine is feasible. |
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