多泥沙电站高水头低出力水轮机水力设计策略

在多泥沙河流运行的水轮机,经常受到严重的泥沙磨损危害,机组的检修周期及运行寿命普遍较低。特别是对于高水头低出力要求的水轮机,机组磨损情况往往更为严重。为提高机组的抗磨损性能,水力设计阶段需专门考虑降低流道流速进而提高抗磨损性能的方法。本文以木扎提河三级水电站小水轮机的设计为例,综合考虑易磨损部位的相对流速及机组水力性能,确定了适用于高水头小流量多泥沙电站的水轮机水力设计策略。研究表明常规降低转速的方法对转轮及导叶出口流速、密封间隙内流动均有显著影响,转速降低的程度应通过流场对比分析合理确定。在高水头电站导叶尾部磨损更为严重,通过采取增大分度圆、优化导叶翼型及相对位置等可有效降低导叶后相对流速。采用长短叶片转轮,可大大降低转轮内部流速,提高在高含沙条件下机组的抗磨损性能,提升水轮机的运行稳定性及安全使用寿命。本文的研究可为多泥沙电站的水轮机设计策略提供有效参考。

Hydraulic Design Strategy for Low Specific Speed Hydraulic Turbine Operating on Sediment-laden River

The hydraulic turbine operating on sediment-laden river is always subjected to serious sand abrasion,which will greatly shorten the unit maintenance period and operating life.Especially for the turbine with high head and low output requirements,the unit wear is often more serious.Anti-erosion characteristic is a critical issue that has to confront with during the hydraulic design.This paper takes the hydraulic design of Muzhati hydropower station as an example,considering the unit performance and relative velocity in three parts that are easy to wear,determined the hydraulic design strategy suitable for high head low specific speed heavy sediment power station.The research showed that it is feasible to alleviate sediment wear by reducing the unit speed within reasonable limits based on its influence at the guide vane and runner.The guide vane wear is the most serious area under high head sediment-laden power plant,which needs to be improved by increasing the pitch circle and optimizing the profile and its relative position.The splitter blade can greatly improve the unit’s antiwear performance under the condition of high sediment laden,and improve the operation stability of the turbine.This research can provide an effective reference for the hydraulic design of hydro-turbine operating on heavy sediment power station.