某航空发动机燃气涡轮叶片低循环疲劳寿命研究

RESEARCH ON LOW CYCLE FATIGUE LIFE OF GAS TURBINE BLADE OF AN AERO-ENGINE

针对目前燃气涡轮叶片更多依赖于后期整机长试才能集中暴露设计不足的问题,以某型发动机燃气涡轮叶片为例,开展了燃气涡轮叶片低循环疲劳寿命研究。首先,在典型循环下开展燃气涡轮叶片应力应变分析,确定了该燃气涡轮叶片的主要失效模式是以应变疲劳控制的低循环疲劳破坏,根据线性损伤累积原理,预测了燃气涡轮叶片的低循环疲劳寿命。然后,创新的提出了一种在旋转试验台实现涡轮叶片低循环疲劳试验的设计方法,采用开环式电磁感应线圈加热叶片,通过热传导实现带温度梯度的燃气涡轮转子温度场,并根据应变等效原则,确定了燃气涡轮转子试验转速。试验结果表明,燃气涡轮叶片预测寿命在5倍寿命分散带以内,且部件试验叶片裂纹位置与整机试验结果吻合。

In view of the problem that the gas turbine blades rely more on the long-term test of the whole machine in the later stage to expose the insufficient design, this paper takes the gas turbine blades of an engine as an example to study the low cycle fatigue life of gas turbine blades. Firstly, the stress-strain analysis of gas turbine blade is carried out under typical cycles. It is determined that the main failure mode of gas turbine blade is low cycle fatigue failure controlled by strain fatigue. According to the principle of linear damage accumulation, the low cycle fatigue life of gas turbine blade is predicted. Then, a design method of low cycle fatigue test of turbine blade on rotating test-bed is innovatively proposed. The method uses open-loop electromagnetic induction coil to heat the blade, realizes the temperature field of gas turbine rotor with temperature gradient through heat conduction, and determines the test speed of gas turbine rotor according to the principle of strain equivalence. The test results show that the predicted service life of gas turbine blade is within 5 times of service life dispersion zone, and the crack position of component test blade is consistent with the test results of the whole machine.