沙尘在风力机叶片表面沉积机理研究

Due to the dust deposition on the surface of the blades,the wind turbine that long-term operates under wind-sand environment will have aerodynamic performance degradation and induce a series of problems,for example, bad blade dynamic balancing, accelerated corrosion and aging of blade materials and so on.But there is a lack of adequate knowledge and understanding for the dust deposition on the surface of the blade.The mechanism of accumulating dust on blades surfaces of horizontal axis-stall regulated wind turbines depends on the otherfactors in site like, sandy storm frequency, wind speed direction surface roughness of blades, topography of site, etc. And, relevant experimental study shows that dust deposition process relates to static electricity. This project intends to adopt combination of theoretical analysis, experimental research and numerical simulation, studying the collision between dust and blade in the process of deposition ,thus obtaining charge transfer model between dust and blades. Based on computational fluid dynamics theory, the discrete element method, the triboelectrification model and the gas solid two phases flow coupling method, the wind-sand movement-electric field coupling model and program will be developed,which is used to simulate the external flow field of baldes under sand-wind environment. The mehcanism of dust deposition on the wind turbine surface could be achived.The study in present project will provide theoretical foundation and basis for efficiently working of a wind turbine under sand-wind environment during long period.

在风沙环境中长期运行的风力机，沙尘等微粒物质可能在风力机叶片表面沉积，使风力机的气动性能下降，并引起风力叶片动平衡变差及叶片材料加速腐蚀、老化等一系列问题。然而，对于沙尘在叶片表面的沉积过程本身，目前还缺乏足够的认识和了解。相关实验研究表明，沙尘的沉积过程与静电有关。本项目拟采用理论分析和数值仿真相结合的方法，对沉积过程中沙尘和叶片的带电行为进行定量研究，通过对风力机气固两相流场进行风-沙-电多向耦合分析计算，研究沙尘颗粒在流场及叶片表面的运动轨迹和受力，分析沙尘沉积过程静电力的作用，探讨沙尘在风力机叶片表面沉积的力学机理，总结沙尘在叶片表面沉积的相关规律，指导风力机风片优化设计和防护，为风沙环境下风力机的长周期高效运行提供理论基础和依据。

在风沙环境中长期运行的风力机，沙尘等微粒物质可能在风力机叶片表面沉积，使风力机的气动性能下降，并引起风力叶片动平衡变差及叶片材料加速腐蚀、老化等一系列问题。然而，对于沙尘在叶片表面的沉积过程本身，目前还缺乏足够的认识和了解。本项目通过引起沙尘沉积的曳力、静电力、液桥力和范德华力等进行深入分析，建立颗粒碰撞过程中的广义粘弹性法向接触力模型、滚动摩擦模型和静电转移模型。通过建立DU35翼型模型，对风力机叶片近流场进行分析，得到了DU35翼型在不同来流和风速下的外流场。通过建立风-沙-电多向耦合平台，研究沙尘颗粒在叶片表面近流场的运动特征及沉积过程。静电力和液桥力是使沙尘颗粒发生沉积的主要因素，初始沉积主要发生在叶片前缘和后上缘，而累加沉积主要发生在叶片前缘。建议通过采用改进叶片材料，可有效防止风力机叶片表面沉积现象发生。