【摘要】 针对一台33kW水平轴风力机,开展了尾流区速度的现场测量实验,得到了风力机尾流区1倍风轮直径断面上部分测点的速度分布,分析了尾流速度的时域和湍流谱特性.研究发现:尾流区1倍风轮直径处,轴向速度亏损较大,测点处的轴向速度亏损率在35.1%–54.17%.铅垂方向速度变化较小,水平方向速度较来流速度的水平分量略有增大,反映出了尾流的膨胀特征.测点处的湍流动能表现出一定的周期性变化规律,尾涡的通过频率与风轮的旋转频率相近.同时,测点处3个方向湍流速度分量的功率谱在低频段均表现出斜率为–1的特性.更多还原

【Abstract】 Wind turbines work in a complex natural environment,where their flow field shows the characteristics of high turbulence levels.Due to the complexity and instability of the atmospheric boundary layer flow,as well as the influence of the scale effect,wind tunnel test cannot reflect the real working condition of wind turbine.So field experiments are very necessary to study wind turbine flow characteristics in actual wind field.In this investigation,field experiments of the wake behind a wind turbine were carried out to get velocity distribution in it.The field experiment system is composed of a 33 kW wind turbine,a 20 m high anemometer tower,a wake velocity measurement platform and the controlling device.The wind turbine is horizontal-axial,two-bladed,upwind-type,with variable pitch angles,14.8 m in diameter.Wake velocity measurement platform is composed of an 18 m high hydraulic lift,anemometer installation platform and three sets of the US CSAT3 three-dimensional ultrasonic anemometer.Inflow parameters were gauged,such as wind speed,wind direction,atmospheric pressure,temperature and humidity.Besides,the operating conditions of the wind turbine were recorded,including pitch angle,yaw angle,rotor speed.It is discussed that the time domain and power spectrum characteristics of wake velocity at a measuring point located at one rotor diameter downwind from the rotor plane.The results show that there are larger velocity deficits in the wake.The axial velocity deficit rate at the measuring point is between 35.1% and 54.17%.The change of the velocity in vertical direction is small.The velocity in lateral direction is slightly larger than the velocity component of inflow,which reflects the expansion characteristics of the wake.Besides,the turbulent kinetic energy at the measuring point shows a periodic variation,and the vortex sheet passage frequency is similar to the rotation frequency of the wind turbine.Meanwhile,all of the power spectra of turbulent velocity in three directions at the measuring point show a characteristic of slope for -1 at the section of low frequency,which mean the turbulent flow is in the classical production subrange.更多还原