Dynamic Characteristics Research Of Gear Coupling Rotor System In High-speed Heavy-duty Gas Turbine

With the increase of rotational speed of gear-rotors and the improvement of its performance, the study of the dynamic characteristic of the gear-rotor system has been becoming a research focus. Because of the gears meshing, bending vibration and torsional vibration of rotors are coupling, so we can't analyze the dynamic characteristic of rotors system with only one rotor. In order to analyze the dynamic characteristic of gear-rotor system, the lateral-torsional coupling vibration modal must be set up.Papers rely on the support of national science and technology project"the Common Key Technology of High-speed, Heavy-duty Gear Drive System", combined with the currently research method of simple rotor dynamic characteristics, to study dynamic characteristic of High-speed, Heavy-duty gas turbine gear-rotor system, which including the critical speed and unbalance response. It has provided reference for the design of gas turbine gear box.Papers briefly introduced the present research of rotor dynamics, and presented the problem facing in domestic research along with the solutions to that problem have realized. Then we described the transfer matrix method for calculating the critical speed and their vibration modal of the rotor system. The bending and torsional vibration issues of simple rotor were studied separately, many transfer matrixes of several typical units were appended. Furthermore, the method to calculate the characteristic of the rotor which supported by sliding bearing was studied. We discussed the method for calculating the dynamic coefficient of sliding bearing along with its dynamic characteristics, and the plural value of the vibration characteristics was intensively researched, as well as the vibration modal. Then the transfer matrix of rotor supported by sliding bearings was deduced. In succession, the paper gave an overview of basic theory of the whole transmission matrix, with this method the whole transmission matrix of multi-axis parallel coupling rotor system was built.Basing on the topic of high speed and heavy duty gas turbine gear-rotor system, the bearing damping, stiffness, gear meshing stiffness, meshing damping, the coupling stiffness and the related parameters of gear-rotor system were studied and discussed,. According to the work above, the coupled stiffness and damping matrix were deduced. Then using the transfer matrix method, the bending vibration modal and the lateral-torsional coupling vibration model of gear-rotor system was established. Moreover, its inherent characteristics were analyzed and calculated. The result shows that, because of the gear meshing, making bending vibration of rotor system coupled with the torsional vibration, which derived some new critical speed and the corresponding mode. Therefore, we should pay particular attention to the impact made by gear transmission when designed the system.Finally, papers analyzed the unbalance response of the gear-rotor system. We can conclude, as the result of the gear coupling effect, when we imposed the exciting force on one rotor, the vibration will be transfer to the others which link together with the running shaft through gear meshing, especially high-speed shaft unbalance will cause intense vibration. Therefore, we should pay attention to improve the precision of dynamic balance of rotor, and reduce the unbalance quantity to improve the dynamic performance of system.