燃气轮机周向拉杆转子拉杆应力分析和改进设计
Strength Analysis and Design Improvement of the Tie Rods in Circumferentially Distributed Rod Fastening Rotors

为优化燃气轮机的拉杆组合式转子中拉杆的结构,提高转子运行安全性,建立了含10根周向均布拉杆的10级轮盘转子模型,设置了8组拉杆凸肩与拉杆孔的静态安装间隙,采用三维接触非线性有限元方法分析了拉杆应力随转速、凸肩静态安装间隙量的变化关系。在此基础上,比较了相同间隙量下凸肩数等跨距加倍和不等跨距加倍对降低拉杆应力的效果,进一步研究了各凸肩等跨距时跨距变化对拉杆应力的影响。结果表明:拉杆凸肩与拉杆孔的静态安装间隙量不影响拉杆在正常工作状态下的应力,但是影响转子升速时拉杆最大应力;随着转速升高,拉杆最大应力在不同的转速区域内存在特定变化规律;增加凸肩数、减小凸肩跨距能够有效减小拉杆最大应力,与不等跨距增加拉杆凸肩数的改进方案相比,等跨距方案降低应力效果更显著。该结论可为燃气轮机的拉杆组合式转子设计提供参考。
A 10？？stage rotor model with 10 circumferential tie rods in uniformly distribution is proposed to optimize the rod structure and to improve the operation safety of the rotor with tie rods in gas turbines. It is based on the model that a series cases of rod shoulder clearances are set, and the relationship among the stress of the tie rod and the rotational speed, and static installation clearance is investigated using a three？？dimensional nonlinear contact finite element method. Then the effects of two improvement plans (double the shoulder number with equal and unequal span respectively) on stress reduction are compared at the same static installation clearance. Moreover, the effect of the span value on the stress of the tie rod is studied while the shoulders are uniformly arranged. Results show that the clearance between the rod shoulder and rod hole has no relationship with the rod stress at a normal operation condition, but affects the maximum stress when rotor speed increases. There exists a specific change rule of the maximum stress of the tie rods in different speed range. The maximum stress of the tie rod is effectively reduced by properly adding the amount of the rod shoulders to reduce the span. The effect of stress reduction obtained by adding the rod shoulder number uniformly is better than that obtained by adding the rod shoulder nonuniformly. The results provide references for the design of the rotor with tie rods in gas turbines