Study On The Method To Determine The Dynamic Scaling Laws Of Complex Rotor System

Complex rotor system refers to the rotor support system composed of a large number of structural members.Taking aeroengine as an example,as an aircraft power propulsion system,its dynamic characteristics are particularly important because of many complex factors such as vibration and noise.The rotor system of aero-engine is composed of many structural parts,which will produce coupling effect between components at high rotating speed and make the vibration problems of the system more complex.In addition,it is difficult to establish the mechanism model of the system or use numerical simulation to accurately determine the dynamic characteristics of the aero-engine rotor system due to the harsh working environment and severe working conditions,so that a large number of tests are required.Compared with the prototype test,the scaled-down model test is widely used owing to its high feasibility,strong human control,low test space and cost saving,and high research efficiency.However,most of the current similitude methods are limited to simple structure or system similitude design,and it is difficult to apply to complex rotor systems with complex geometry,coupling scaling laws and multi structures coupling vibration.Therefore,the main goal of this paper is to establish a method for determining the scaling laws of complex rotor system,which can also be utilized to other complex systems with the same characteristics.For the complex rotor system,the straight blade as the research object firstly in this paper and the traditional similarity approach is combined.On this basis,a novel scaling laws determination method is established and applied to rectangular plates with complex geometry and different boundary conditions and rotor-bearing system.Finally,the blades and rotor-bearing system are integrated into a complex rotor system,based on the study of the influence of the coupling vibration characteristics of the system,the scaling laws of dynamic characteristics are established according to actual needs.The paper mainly concludes the following 4 research contents:(1)Based on the vibration theory of plate and shell,the linear and nonlinear dynamic models of the straight blade are established.Then,combining the traditional scaling laws algorithm,the similar design parameters are obtained by analyzing the vibration response mechanism and considering the damping effect.The feasibility of vibration characteristics calculation techniques and the accuracy of scaling laws are verified through simulation and vibration test.(2)The Lagrange Energy-Least Squares based Similitude Method is proposed and applied to the rectangular plate with varies of through holes and boundary conditions.The coupling effect of support stiffness on geometric dimensions and material scaling laws is analyzed and eliminated,Comparing with the traditional similarity approaches,meanwhile,establishing the two-dimensional structural size intervals of scaling laws.The numerical simulation results and distorted scaling laws are verified by experimental tests.(3)For the rotor-bearing system,the vibration characteristics of the prototype system are predicted by the LE-LSSM,and the coupling scaling laws are calculated by the Discrete Iteration Method.The coupling scaling laws are verified by predicting the vibration characteristics of the prototype with single parameter and multi parameters geometricdistortion models.(4)For the complex rotor system,the influence of structural parameters on the natural characteristics of the system is analyzed.Through sensitivity analysis and the LE-LSSM,the partial scaling laws of geometric and structural parameters are established,and the accuracy of the scaling laws is verified by numerical simulation.