Study On Nonlinear Dynamic Characteristics Of Single And Double Span Rotor System With Oil Film Bearing

Rotary machinery for the rotor system is widely used and often used in some important and special occasions,so the stability of the rotor operation is very important.People through the study of major rotor accidents and analysis,found that in many cases the instability of the rotor system movement is caused by the role of many non-linear force,then if you want to fundamentally solve the problem,you must abstract object from the specific problems and the establishment of mathematical model to analyze the operating characteristics of the rotor system under the action of nonlinear force,so as to obtain the condition and parameter data which is favorable for the rotor to run smoothly.In this paper,the dynamic characteristics of the rotor system are analyzed under the action of strong nonlinear force film force,rubbing force and centrifugal force.Under the assumption that the rotor disc mass distribution is uneven,there are eccentricity and the rotor bearing is not medium condition,a single disk oil film bearing rotor system model and a double-span multi-disc rotor system model under the oil film force support are established.Firstly calculating the oil film force with Renault formula and then listing the equations of the rotor system,finally the numerical equations of the system are numerically simulated by the fourth-order Runge-Kutta method.The influence of the change of the parameters of the rotor system on the system solution is illustrated by using the bifurcation diagram,phase diagram,Poincare map and time history.Through the analysis of their changes under the influence of the nonlinear force,what kind of system parameters will be selected to minimize the occurrence of rotor friction,the rotor running stable.The results show that For the double-span multi-disk oil-film rotor model,when the stator stiffness value increases and the low speed of the rotor movement,the system is stable and unchanged,in other areas have a large number of chaotic almost periodic motion,so choosing a smaller stator stiffness;for the rotor stiffness value changes,when it increases,the lower and higher speed of the rotor system is not affected,the medium speed will gradually appear in a large number of chaotic almost periodic area,So to ensure a large enough anti-deformation ability,select a relatively small stiffness value;When the quality of the disc changes,the system is less affected and the movement is always very stable in the low-speed area,but in high-speed region,as the quality of the disc increases,the system becomes more unstable,so trying to choose a smaller quality value;When the coefficient of friction increases,the effect on the system is small,so choosing the appropriate size of the value,to avoid serious grinding area;When the rotor damping value is gradually increased,the rotor in the medium and high speed area appears almost periodic and the phenomenon of complex periodic motion is obviously reduced,and When the disk damping value continues to increase,the effect on the stability of the rotorbegins to decrease,so choosing a properly large disc damping value when we choose;for the quality of the bearing change,the impact is small in the low speed region,in the medium speed region the impact is great,so it is best to choose a smaller bearing quality value.Through the analysis of the impact of the above parameters on the system response,it can help to select reasonable and stable operating parameters in the process of rotor work and manufacturing.