The Study Of Wake Structure Of Horizontal Axis Wind Turbine And Its Effects On Farms Layout

Energy is the important base material of national economy and also the main living conditions of human being. The speed of the development of economy and the improvement of people’s standard of living depends on supplies of energy. Ecology deterioration problem become more and more serious as the growing depletion of the traditional fossil energy and the development of the industrialization.Not only cover range become wider, but also the degree of pollution is become more serious. Wind power as a kind of clean renewable energy gets more and more people’s attention. The spacing between wind turbines is as big as possible in order to ensure the power of each turbine is not affected. In that way the turbines are not affected by the wake of adjacent wind turbine. The turbines will work in the optimal state. However the area of the wind farm will become lager and also increase the length of cable between the wind turbine and the grid. The economic costs will be improved greatly. Therefore the spacing of turbines is as small as possible. That will make some turbines in the wake of upstream turbines. The performance and efficiency of downstream wind turbine will be affected on account of the upstream wind increase the turbulence intensity in oncoming flow. That will further impact on the power output of wind farm. Therefore it’s necessary to study the wake influence between turbines.The goal is to optimize the wind farm. The main work of this thesis is study the wake influence of turbine in different array. Due to the existing experimental data are mainly for the wake field of single wind turbine, and the experimental data about array of wind turbines are rarely.In that way this thesis is mainly about the measurement of the wake field of different array of turbine by pitot tube and anemometer. And the conclusions is verified by numerical simulation. The qualitative rules of wake field are obtained through comparing the results of experiment and numerical simulation. The main contents and conclusions are as follows:(1)Studying the velocity field and pressure field of wake of single turbine based on experiment and numerical simulation. And the data of single turbine provides an evaluation for the wake field of different spacing between two rotors co-axial arrangement and stagger arrangement. Qualitative conclusions about the influence between two wind turbines can be getting. It turned out that the velocity field and pressure field of wake of downwind turbine significantly reduced by reason of influence of wake of the upwind turbine when co-axial wind conditions. At the same time the power of downwind turbine also have been affected. However the downwind turbine is not only affected by the wake from the turbine in same row, and interfere with the wake of upwind when staggered arrangement.(2)Actuator disk model is used to study the wake of two rotors co-axial arrangement in wind farm. The power obtained by the actuator disk of constant load is less than the actual data of wind farm. This is mainly due to the pressure obtained from the actuator disk method which using BEM method is mean pressure rather than the actual pressure on rotor. Thus lead to the pressure difference is less than the actual situation. In that way the power loss between the first turbine and the downwind turbine is about35%.And the power is slightly decreased with the development of wake.