涡扇发动机涡轮带冠叶片叶尖间隙测试

Research on tip clearance measurement of shrouded turbine blades of turbofan engine

航空发动机叶尖间隙参数的在线高精度测量是保证发动机运行安全和气动效率的关键。涡扇发动机低压涡轮叶片为叶顶带有篦齿结构的带冠叶片,传统电容式叶尖间隙传感器为圆形芯极结构,其测量精度易受变工况下篦齿轴向窜动影响。因此提出一种矩形芯极的电容传感器结构方案,基于双极板电容原理,建立矩形芯极下的叶尖间隙测量模型。仿真分析轴向窜动对不同结构传感器方案的影响规律。开发矩形芯极传感的带冠叶片叶尖间隙测量系统,搭建测试平台,开展实验室环境下的标定和测量实验。仿真和实验结果表明:新型的矩形芯极传感器可提高传感器的抗轴向窜动能力;1~3 mm量程内,叶尖间隙测量误差小于65μm。

High precision online measurement of blade tip clearance parameters is the key to ensure the safety and aerodynamic efficiency of aeroengine.The low pressure turbine blades of turbofan engine are covered with sealing labyrinth at the top.The typical capacitive sensor of blade tip clearance measurement is designed with circular core structure,which makes the measurement accuracy easily affected by the axial movement of blades under varying working conditions.Therefore,a new kind of capacitance sensor with rectangular core electrode structure is invented.The blade tip clearance measurement model based on the new sensor is established using the bipolar plate capacitance principle.Effects of the axial movement of blades on different structure sensors is simulated and analyzed.The tip clearance measurement system of shrouded turbine blades based on the sensor with rectangular core electrode was developed.The test platform was built,and the calibration and measurement experiments in the lab were carried out.Simulation and experimental results show that the new type sensor with rectangular core electrode has good performance faced with the axial movement of blades.The measurement error of blade tip clearance is less than 65μm in the range of 1 mm to 3 mm.