涡轮叶片裂纹故障的3维叶尖间隙变化特性分析

Analysis of 3D Tip Clearance Variation Characteristics for Cracked Turbine Blades

为了分析涡轮叶片裂纹故障的3维叶尖间隙动态变化特性,以3维叶尖间隙动态测量试验台上的模拟涡轮转子为研究对象,建立了涡轮叶片3维叶尖间隙的有限元分析模型;采用数值仿真分析方法分别深入地分析了无裂纹涡轮叶片和不同长度裂纹叶片3维叶尖间隙的动态变化特性。结果表明:对于无裂纹涡轮叶片,气动载荷会导致其发生弯曲变形,进而,导致轴向偏转角呈先增大后减小的变化趋势,周向滑移角则逐渐减小,并且气动载荷对轴向偏转角和周向滑移角的影响比对径向间隙的影响更为显著;对于有裂纹涡轮叶片,在气动载荷、离心载荷、叶片尾缘裂纹故障以及叶片自身形态等多种因素的共同影响下,导致径向间隙呈现逐渐增大,而轴向偏转角和周向滑移角均呈现逐渐减小的变化趋势。

To analyze the dynamic variation characteristics of the three-dimensional(3D) tip clearance for cracked turbine blades, the finite element model of 3D tip clearance of turbine blades was established based on the simulated turbine rotor on the test rig for dynamic measurement of the 3D tip clearance. In-depth numerical simulations were performed to analyze the dynamic variation characteristics of the 3D tip clearance of turbine blades without cracks and with cracks of different lengths. The results show that for the turbine blade without crack, the aerodynamic load will lead to the bending deformation of the blade. The axial deflection angle increases first and then decreases, while the circumferential deflection angle decreases gradually. Besides, the influence of aerodynamic load on the axial deflection angle and circumferential deflection angle is more significant than that on the radial clearance. For the turbine blade with crack, under the combined effect of the aerodynamic load, centrifugal load, crack on the trailing edge of the blade, and the shape of the blade, etc. the radial tip clearance increases gradually, while the axial deflection angle and circumferential deflection angle decreases gradually.