风沙环境下水平轴风力机的转矩特性

Torque characteristics of horizontal-axis wind turbine in sand-blowing environment

在保证外场实验风力机风轮几何相似、运动相似的条件下,结合RNGk-ε湍流模型和DPM模型求解三维不可压缩雷诺平均N-S方程,对外场实验机组的缩比模型进行数值计算,采用虚拟风洞的方法研究了风沙环境下模型风轮的转矩特性,得到在某一风速时,模型风轮的转矩随沙尘颗粒粒径和体积分数变化的规律,并通过与洁净空气时风轮的转矩进行对比分析,研究风沙流对风力机输出转矩的影响规律.研究结果表明,风沙环境会引起风轮转矩的增加,风轮转矩随沙尘体积分数的增大先增大后减小,随沙尘颗粒直径的增大,先增大后减小,最后趋于平稳,沙尘颗粒直径对风轮转矩的影响存在一个敏感区域,沙尘体积分数越大,该敏感区域越大;风沙流对风力机叶片的流动状态影响较小,当绕翼型的流动为湍流流动时,沙尘颗粒的存在会加剧流动的紊乱性,当为层流流动时,沙尘颗粒对流动的扰动较小,反映出较好的跟随性.

Guaranteeing geometric and kinematic similarity of wind turbine rotor for field experiment and employing RNG k-ε turbulence mode and the DPM model, the three-dimensional incompressible Reynold time-average equations were solved and numerical calculation of scaled model of field-experiment wind turbine rotor was performed. A virtual wind tunnel of the rotor model in wind blowing environment method was used to investigate the torque characteristics and the variation pattern of the torque with sand particle diameter and sand volume fraction was obtained when the wind speed was identical. By comparing the rotor torque in clean air to that in sand blowing flow, the influence of sand blowing flow on the rotor output torque of the wind turbine was investigated. The investigation result showed that sand blowing flow would result in increase of rotor torque. The rotor torque would increase at first and then decrease with the increase of sand volume fraction And the torque would increase at first and then decrease with the increase of sand particle diameter, and finally tended to be stable. There was a sensitive range in the process of influence of sand particle diameter on rotor torque, where the larger the volume fraction was, the wider the sensitive range would be. The effect of sand blowing flow on the flow state around wind turbine blades was insignificant. When the flow around airfoil was turbulent, the sand particles would increase the disorder of the flow. When the flow was laminar, sand particles played less role in flow disturbance, exhibiting a good follow-up behavior in laminar flow.