高压涡轮盘疲劳载荷分析与试验

Analysis and Test of High Pressure Turbine Disk Fatigue Load

针对航空发动机涡轮盘低循环疲劳寿命受交变热应力影响的问题,对某型高压涡轮盘服役过程的温度场变化情况进行了研究。根据某型发动机高压涡轮盘试车过程中实测的随时间变化的温度分布,采用有限元方法分析了轮盘温度变化对不同考核部位应力水平的影响,对发动机工作状态下各考核部位的循环应力进行了计算。制定了试验方案,设计了试验装置,在旋转试验器上进行了涡轮盘在高温状态下的低循环疲劳试验,按照安全寿命法确定了盘心和螺栓孔部位的安全寿命。结果表明:温度变化对轮盘考核部位应力的影响明显,瞬态温度沿径向呈“V”型分布,导致螺栓孔部位应力水平比稳态温度分布下的提高了25.9%,使其成为涡轮盘的限寿部位;轮盘失效模式为低循环疲劳破坏,裂纹起源于螺栓孔的6、12点钟方向,沿径向扩展导致轮盘失效。

Aiming at the effect of alternating thermal stress on the low cycle fatigue life of turbine disks,the temperature variation field of a high pressure turbine disk during its service process was studied.Based on the measured temperature distribution field time history of the high pressure turbine during the engine test,the effect of temperature field variation was analyzed using FEM to assess the stress level at verification locations of the disk.The cyclic stresses at these locations under engine operating conditions were calculated.The LCF test plan was formed,the test apparatus was designed,and the high temperature LCF test of the turbine disk was carried out on the spin test rig.The safe lives of the disk core and bolt hole locations were determined according to the safe cyclic life approach.The results show that temperature variation has an obvious effect on the stress levels of the above locations of the disk,the transient temperature is distributed in a“V”shape along the radial direction,resulting in a 25.9%stress level increase at bolt hole locations compared with the stress level under steady-state temperature distribution,making them life-limited locations of the turbine disk.The failure mode of the turbine disk is low cycle fatigue failure,with cracks originating at the 6 and 12 o’clock direction of the bolt-hole,propagating radially leading to the eventual failure of the disk.