Investigation On Lubricationg Characteristics And Active Control Of Fixed-tilting Pad Bearing With Flexible Pivot

As modern advanced power equipment,high-performance gas turbines realized power output and transmission through energy conversion.Therefore,it has received great attention from the energy and military departments of various countries.With the development of high-performance gas turbines towards high reliability,the requirement of high operation stability is put forward for the fixed-tilting pad bearing-rotor system.This dissertation mainly investigates the lubrication performance and the active control method of the fixed-tilting pad bearing,as well as the dynamic characteristics of the fixed-tilting pad bearing bearing-rotor system.The main research works are as follows:1.For the fixed-tilting pad bearing,a lubricating model is established with consideration of the flexibility of the pivot of tilting pad.By analyzing the force characteristics of the tilting pad and solving the lubrication model,the oil film pressure distribution of the bearing is obtained,and then the influence of geometry parameters of the bearing on the flow rate,load-carrying capacity,friction coefficient,power loss,and temperature rise of the lubricant at the static equilibrium position is investigated.2.By considering the friction heat of lubricant in the fixed-tilting pad bearing,the evolution law of the realistic rheological properties of the lubricant is analyzed,and then a thermo-hydrodynamic lubrication model based on the generalized Reynolds equation,energy equation,and heat conduction equation is developed for the bearing with flexible pivot.Based on the model,the hydrodynamic pressure and temperature distributions are investigated,and then the influence of lubricant thermal effect on the lubrication performance is analyzed.3.A nonlinear dynamic model is developed for a rotor system supported by the fixed-tilting pad bearing with flexible pivot.The dynamic responses of the rotor system are solved by the Newmark method.On this basis,the traj ectory map of rotor center,Poincare map,and time series are adopted to analyze the motion law of the rotor system,and the influence of different speeds,preloads,and pivot ratios on the dynamic responses of the rotor system is also analyzed.4.To improve the stability of the fixed-tilting pad bearing-rotor system,an active lubrication control strategy is proposed,and a PID control algorithm is developed for the active lubrication of the bearing.On this basis,the nonlinear dynamic responses of the rotor system under the active lubrication condition and the influence of active lubrication control on the motion of the rotor system are investigated by the developed dynamic model.