| Rotating machinery is widely used in the industrial field,and the stability of its rotor system has a direct impact on production safety and efficiency.Under the background of carbon peaking and carbon neutrality,China’s low-carbon economy has developed rapidly,and the energy structure has changed with each passing day.Gas turbines play an important role in the field of national energy development and national defense security due to their advantages such as rapid start-up and shutdown,high thermal efficiency,and environmental protection.The dynamic design and vibration fault characteristic analysis of gas turbine rotor systems have become bottleneck issues in China’s gas turbine development,and the lack of effective modeling and analysis methods for rod rotors is one of the reasons for this problem.In this paper,dynamic modeling method of multi-disk rod fastening rotor system is proposed based on the structural characteristics of gas turbine rotor system.Crack and rub-impact faults are introduced to establish dynamic models of the multi-disk rod fastening rotor system under different fault conditions.The dynamic characteristics of dual-disc rotor-bearing system and multi-disk rod fastening rotor system under parameter changes and fault coupling effects are studied.The fault characteristics and dynamic behavior of the rotor-bearing system and the multi-disk rod fastening rotor system are partially verified through simulation experiments of different degrees.types,and coupling faults on the rotor experimental platform.The main research and results are as follows:(1)This paper elaborates on the nonlinear dynamic theory related to rotor system.Taking the dual-disc rotor-bearing system as an example,dynamic modeling and simulation analysis of the system are carried out.The effects of crack,rub-impact,and parameter changes on the vibration characteristics of the rotor-bearing system are studied.The research results indicate that the crack,rub-impact and coupling effect of multiple faults suppresses oil whirl of the rotor-bearing system.The increase of stator stiffness reduces the amplitude of the rotor-bearing system with multi-fault,simplifies the dynamic behavior,and improves the stability.The change characteristics of dynamic behavior for the rotor-bearing system are obtained,which.provides theoretical foundation for the dynamic modeling and characteristic analysis of gas turbine rod fastening rotor system.(2)A dynamic modeling method for multi-disk rod fastening rotor system is proposed based on the structural characteristics of gas turbine rotor system.In the method,the multi-disk structure of the system,nonlinear oil film support,and contact effects between disks are fully considered.Rub-impact is introduced,and dynamic model of a multi-disk rod fastening rotor system under rub-impact is established.The influence trend of parameter changes on the dynamic behavior of the rod fastening rotor is compared and analyzed.The consistency of the dynamic characteristics changes between the multi-disk rod fastening rotor system and the dual-disc rotor-bearing system under the action of rub-impact is revealed.The analysis results indicate that increasing stator stiffness and reducing static clearance simplify the nonlinear behavior of the rod fastening rotor system and improve system stability,which is consistent with the influence of stator stiffness on the rotor-bearing system.The reduction of static clearance delays the first bifurcation of the system and suppresses oil whirl.The increase of eccentricity can simplify the nonlinear behavior of the system.Increasing the radial clearance intensifies the oil whirl and improves the system stability in the medium and high speed range.The analysis results provide a theoretical basis for identifying the dynamic characteristics and detecting rub-impact faults of gas turbine rotors.(3)Crack fault was introduced to establish a dynamic model of multi-disk rod fastening rotor system with crack.The dynamic characteristics of the rod fastening rotor system are studied under the combined effects of contact effect,crack fault,and nonlinear oil film force.The influence of different system parameters on the nonlinear behavior and stability of the system is analyzed.The consistency of dynamic characteristics for the multi-disk rod fastening rotor system and the dual-disc rotor-bearing system under crack is revealed.The research results indicate that crack delays the first bifurcation of the system,narrow the speed range of oil whirl,and suppress the occurrence of oil whirl,which is consistent with the impact of cracks on the dynamic characteristics of the rotor-bearing system.The increase of eccentricity intensifies the oil whirl,changing the range of periodic and quasi periodic motion in the medium and high speed region.The research results are helpful for the crack dynamics analysis and fault detection of gas turbine rod fastening rotor.(4)Introducing crack and rub-impact faults into the multi-disk rod fastening rotor system,a dynamic model of multi-disk rod fastening rotor system under multiple faults is established.The multi-fault dynamic characteristics of the multi-disk rod fastening rotor system are analyzed,and the effects of multi-fault coupling and parameter changes on the nonlinear behavior of the system are studied.The analysis results and the influence trend of multiple faults on the dynamic characteristics of the dual-disc rotor-bearing system are compared.The results indicate that the coupling effect of multiple faults delays the oil whirl of the multi-disk rod fastening rotor system,which is consistent with the multi-fault coupling effect of the dual-disc rotor-bearing system.Increasing the static clearance and reducing the stator stiffness weaken the influence between multiple faults,simplifying the system dynamics behavior and making it easy to observe.The research results provide theoretical reference for multi-fault dynamic feature recognition and fault diagnosis of gas turbines.(5)Simulation experiments of different degrees,types,and coupling faults are crarried out on the rotor experimental platform.The results indicate that in rotor experiments with crack faults,the increase of crack depth significantly increases the amplitude of the fundamental frequency component.The crack fault greatly reduces the speed range of oil whirl in the oil-film support dual-disc rotor test rig.In rotor experiments with rub-impact,the aggravation of rub-impact causes the half fundamental frequency of the system to disappear,suppressing the oil whirl.The aggravation of rub-impact simplifies the nonlinear behavior of the experimental platform to a certain extent.For multi-fault rotor experiments,the coupling effect of multiple faults suppresses the oil whirl of the system,and P2 motion evolves into quasi-periodic motion,enhancing the instability.The experimental results partially verified the simulation results of the fault characteristics and trends for the dual-disc rotor-bearing system and the multi-disk rod fastening rotor system.The research results of this paper provide theoretical guidance for the dynamic design,stable operation,fault feature recognition,and fault detection of gas turbine rotor system.The experimental results have partially verified the simulation of the fault characteristics and variation trends of the dual-disc rotor-bearing system and the multi-disk rod fastening rotor system. |
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