高速液滴撞击下叶片表面微结构防水蚀性能研究

Study on Water Droplet Erosion Resistance by Blade Surface Microstructures Under High-Velocity Droplet Impact

为了有效解决汽轮机叶片的水蚀问题,提高汽轮机运行的安全稳定性,基于水蚀频发位置的结构特点和水蚀特征,提出一种叶片表面微结构的防水蚀方法。这类方法中所包含的叶片表面微结构能在不影响叶型性能的前提下达到较好的防水蚀作用。基于防水蚀机理、结构经济性等多方面考量,设计了沟槽、条纹、球窝、球凸和锯齿共5种表面微结构,并采用两种叶片材料制成标准件及5种带结构试件,在团队自主设计的水蚀测试系统内进行水蚀性能试验。提出平均体积损失作为评价不同结构试件水蚀特性的参数,并使用无量纲抗水蚀性能参数进行对比排序。研究发现:在叶片材料表面布置锯齿形微结构后,叶片材料表面的抗水蚀性能最好,其抗水蚀性能系数是平面的1.57倍;布置条纹、沟槽、球窝3种结构均能在不同程度上提升表面抗水蚀性能。研究结果可为实际叶片防水蚀提供参考。

This paper proposes a method based on blade surface microstructures to solve the problem of water droplet erosion(WDE)of turbine blades and improve the safety and stability of turbine operation.This method is devised based on the structural characteristics and WDE characteristics at the location where WDE occurs frequently.Such microstructures can achieve better effect in WDE prevention without affecting the performance of the blade.Following the WDE resistance principles and given structural economy,this paper designs five kinds of microstructures:grooved,striped,dimpled,protruded and serrated.Two kinds of blade materials are used to make standard test-pieces and five kinds of microstructural test-pieces.The WDE experiment was carried out in the WDE test system self-developed for this purpose.The average volume loss is proposed as a parameter to evaluate WDE resistance by different structural specimens,and the dimensionless WDE resistance performance parameters are used for comparison.It is found that the serrated microstructure has the best WDE resistance,with a WDE resistance coefficient 1.57 times that of a plane structure.Striped,grooved and dimpled microstructures can also improve the surface WDE resistance coefficient in varying degrees.The research data provided by this paper can be a reference for WDE resistance in the actual engineering field.