风电叶片雷击载荷与气动载荷共同作用机制研究

Lightning strike is one of the important factors causing wind turbine blade damage. The superposition of lightning arc and airflow in time and space, combined action, cause blades damage. This process involves a multidisciplinary intersection and multiplephysical coupling of electrical-thermal-mechanical-fluid-solid, which makes it hard to conduct a direct study. Around the problem of lightning stroke multiplephysical coupling, an equivalent load model of lightning strike is put forward in this projects, the lightning arc is equivalent to thermal load and impact force load. The main contents of the investigation are focused on 1) based on finite element of thermal-electric coupling method and Maxwell's equation, study and establishment on the equivalent load model of lightning strikes, 2) the model is evaluated and revised by lightning strikes experiment and finite element calculation, 3) obtain the aerodynamic load distribution of blades based on computational fluid dynamics method, take the aerodynamic load and equivalent load of lightning strike are applied to the blade structure domain, study on the interaction mechanism of two kinds of loads. This investigation is aimed to 1) clarify the equivalent relationship between lightning strike parameters and thermal and force loads, 2) establishment the high-precision equivalent load model of lightning strikes, 3) reveal the interaction mechanism of aerodynamic load and lightning load. The outcomes of this investigation will help to clarify the lightning strike damage mechanism of blades, and are expected to provide scientific support for reliability estimation of wind turbine blades involving lightning strike damage and improvement of wind turbine lightning protection system.

雷击是造成风电叶片损坏的重要因素之一。雷击电弧与气流在时空上相互叠加、共同作用，导致叶片损伤。这一过程涉及电-热-机-流-固等多学科交叉、多物理场耦合，较难直接研究。围绕雷击的多场耦合问题，拟申请项目提出一种雷击等效载荷模型，将雷击电弧等效成热载荷与冲击力载荷。拟研究：1）基于有限元热-电耦合模型及麦克斯韦电磁方程，研究并构建雷击等效载荷数学模型；2）通过模拟雷击实验和有限元计算对模型进行评估并修正；3）基于CFD方法，获得叶片气动载荷，将雷击载荷与气动载荷共同作用于叶片结构域，研究两种载荷共同作用机制。拟达目标：厘清雷击参数与热、力载荷之间的等效关系；建立高精度雷击等效载荷模型；揭示雷击载荷与气动载荷共同作用机制。课题的完成有助于厘清叶片雷击损伤机理，为涵盖叶片雷击损伤的可靠性评估、残余寿命评估和叶片防雷结构优化提供科学依据。

雷击是造成风电叶片损坏的重要因素之一，也成为制约风电机组运行可靠性水平提升的瓶颈问题之一。现有风电叶片雷击防护系统失效率高，叶片雷击损伤率高，在业界已成共识，但对其失效率高的原因及风电叶片雷击接闪机理还尚未研究清晰。虽业界正极力寻求一种高效、可靠的雷击防护系统来解决此问题，但由于实验条件、研究基础等问题，未见有较好的解决方案。基于此，本报告采用模拟雷击实验方法、数值模拟方法，首先研究了现有叶片雷击失效率高的原因，揭示了风电叶片雷击接闪机理；其次建立大容量风电叶片雷击仿真模型，并基于雷击仿真模型，分析了风电叶片雷击概率风险。主要研究内容如下：.1）针对风电机组运行过程中，叶片处于不同相位角状态。研究了叶片相位角对雷击接闪的影响，分析了叶片现有接闪系统雷击失效的原因。.2）自然界雷云存在正极性、负极性之区别，研究了正、负极性下行先导对叶片雷击接闪的影响，得到不同极性雷击接闪的区别。.3）野外风电叶片表面时常存在污秽，研究了当叶片表面存在污秽时，叶片雷击接闪特性。.4）碳纤维复合材料是风电叶片超大型化发展的主要材料，研究了碳纤维铺层叶片雷击接闪特点。.5）建立了大容量风电叶片雷击接闪仿真模型。.6）基于雷击仿真模型，分析了大容量风电叶片雷击接闪失效概率风险。