燃气轮机转子分布式拉杆螺栓螺纹受载和松动特性

Load and loosening characteristics of distributed tension rod bolt thread in gas turbine rotor

针对燃气轮机转子分布式拉杆螺栓螺纹载荷分布不均匀以及松动特性,研究公制螺纹、内锥螺纹、带卸荷槽公制螺纹和带卸荷槽内锥螺纹等4种形式的拉杆螺栓的螺纹载荷分布,分析各螺纹牙载荷分布特点,结果表明带卸荷槽的内锥螺纹牙载荷分布最均匀。针对燃机转子运行时的载荷特点,采用有限元准静态方法模拟多种载荷因素作用下拉杆螺母的松动过程,研究预紧力和第一扣螺纹最大滑移量在不同载荷作用下的变化,结果表明:转子弯矩不会导致螺母松动,多次短路扭矩累积导致预紧力大幅减少,横向载荷持续作用下预紧力缓慢减小,拉杆螺母发生松动;在3种载荷分别作用下,带卸荷槽的内锥螺纹预紧力减小幅度最小。

As to the uneven load distribution and loosening characteristics of distributed tension rod bolts for gas turbine rotors,the thread load distributions of the tension rod bolts in four forms are studied,which are the metric thread,the internal cone thread,the metric thread with unloading groove,and the internal cone thread with unloading groove.The load distribution characteristics of each thread tooth is analyzed.The results indicate that the load distribution of the internal cone thread with unloading groove is the most uniform.Regarding the load characteristics of gas turbine rotors during operation,the loosening processes of the tension rod nuts under various load factors are simulated using finite element quasi-static method,and the preload force variation and the maximum slips of the first thread under different loads are studied.The results show that:the bending moment of the rotor will not cause the nut loosen,and the accumulation of multiple short circuit torques leads to a significant reduction in the pre-load force,and then under the continuous action of lateral loads,the pre-load force slowly decreases,and the tension rod nut becomes loose;under three different loads,the reduction in pre-load force of the internal cone thread with unloading groove is the smallest.