| As a green renewable energy, wind energy development has attracted worldwide attention. Wind turbine is one of the main machinery utilization of wind energy resources, and gradually the trend toward large-scale development, but due to environmental factors, the measurement error constraints, computing resources, and other factors, on the horizontal axis wind turbine aerodynamic performance estimates are often inexperienced, cause large errors.The wind tunnel test and field test for the wind turbine performance prediction is often encountered interference in various environmental factors, coupled with the Reynolds number effects cannot be avoided, the accuracy affect the test results. In order to solve the above problem, based on fluid mechanics similarity theory, the approximation method, in view of the two blade wind turbine for the three-dimensional steady flow field calculation. By comparing the calculation results of approximate model, carries on the analysis from the blade surface flow characteristics and force characteristics, the approximate model method is the most suitable similarity calculation of wind turbine. Here, on the basis of approximate model to verify the shrinkage ratio of optimum scope of application. And then through the three blade of large-scale wind turbine numerical verification, the results show that the model under various working conditions wind turbine blade surface is similar to prototype to keep flow characteristics and load characteristic. The whole process of the research to strengthen the understanding of wind turbine aerodynamics, and the similarity theory and aerodynamics are soft, form the theoretical calculation method numerical a complete wind turbine similar, summarized as follows:(1) two wind turbine blade by numerical calculating results only meet the geometric similarity and tip speed ratio equal is not sufficient, especially strongly separated flow in the wind turbine operation process, results and prototype results vary greatly.The two wind turbine blade geometry model of three-dimensional numerical calculation results showed that the Froude model and the Reynolds model method, Reynolds model method to meet the Reynolds similarity criterion and related parameters proportional relationship, can effectively shrink ratio blade surface flow model and the prototype in similar circumstances, and on the blade surface pressure coefficient of torque, axial force and the relative error is within2%, thus determining Reynolds model method as the most suitable for wind turbine geometry scaled model research program. The results in this study based on the range of the ratio, control in2.027%to10.135%between the geometric model, the model and the prototype of the relative error is within5%.(2) The complete similarity theory was applied to large wind turbine blades, verified by the calculation results of several similar cases. Research shows that the model and the prototype using Reynolds model method of wind wheel flow characteristic and force characteristic calculation results were similar; the average relative error is maintained at around1.5%. The large leaf blade wind turbine with a Reynolds model can also be in the shrinkage ratio of effective and accurate response of the flow characteristics, the large wind turbine aerodynamic performance prediction reliability is high.(3) According to the results of the two blade model, studied the influence of Reynolds model of Reynolds number, turbulent viscosity and leaves of normal force coefficient and tangential force coefficient, obtained the following conclusions:Reynolds model through similar conversion, increase the number of Reynolds wind turbine model effectively reduced to order of magnitude and prototype of the same, that is, the relationship between geometric similarities, but also to meet the Reynolds similarity criterion. By comparing the turbulent viscosity, found the Reynolds model method model, the eddy current area with strong turbulence viscosity, high flow smoothly; in the case, the turbulent viscosity is reduced accordingly, test conditions without changing the viscosity to low. And Reynolds number model on leaf normal force coefficient and tangential force coefficient has certain regularity. In the same geometric ratio conditions, to force coefficient and tangential force coefficient than the method without using the results calculated by low Reynolds model method. |
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