某级压气机转子叶片高周振动疲劳强度储备分析研究

Study on Fatigue Strength Reserve of High Cycle Vibration of a Compressor Rotor Blade

为完成某型燃气轮机压气机新设计转子叶片高周疲劳储备分析,采用基于叶尖定时法的激光非接触测量方法对该级转子叶片进行了振动应力测试,并结合理论计算和转子叶片高周疲劳极限试验,获得每一只叶片的高周振动疲劳强度储备,创新性地一次性完成了某级压气机新设计转子叶片振动疲劳性能的全面评估。研究表明:理论计算得到的叶片1阶弯曲共振转速为4 393 r/min,实测叶片在机组全部运行工况下的共振转速区间为4 276~4 435 r/min,叶片振动应力范围为54~123 MPa;试验实测得到的置信度满足95%及误差限度5%下叶片中值疲劳极限为730 MPa,推算得到99.99%高存活率下叶片高周疲劳极限约为660 MPa;结合叶片静强度分析结果、叶片材料的抗拉强度值、叶片振动应力值和99.99%高存活率下叶片的疲劳极限值进行计算,其高周振动疲劳强度最低储备为4.61,共振转速区间处于机组运行的过渡工况,满足设计要求。

In order to complete the high cycle fatigue reserve analysis of a new design rotor blade of a gas turbine compressor, using the laser non-contact vibration stress measurement method based on blade tip timing method combined with theoretical calculation and high cycle fatigue limit test of rotor blade to obtain the high cycle vibration fatigue reserve of each blade.A comprehensive evaluation of vibration fatigue performance of the newly designed rotor blade of a compressor has been completed innovatively.The results show that the theoretical calculation of first-order bending resonance speed of the blade is 4 393 r/min, the measured resonance speed range of blades in the whole operating condition of the unit is 4 276 r/min to 4 435 r/min, and the vibration stress value of blades is 54 MPa to 123 MPa.The median fatigue limit value of the blade is 730 MPa with 95% confidence and 5% error limit, and the high cycle fatigue limit of blade is approximately 660 MPa when the high survival rate is 99.99%.The vibration fatigue of this stage blade is obtained by combining the static strength analysis result, the tensile strength value of blade material, the vibration stress value and the fatigue limit value at high survival rate 99.99%of the blade.The minimum reserve of high cycle vibration fatigue strength is 4.61,and the resonance speed is taken as the transition condition of the whole operation, which meets the design requirements.