动载荷作用下中介轴承的非线性热行为研究

NONLINEAR THERMAL ANALYSIS FOR THE INTER-SHAFT BEARING UNDER THE DYNAMIC LOAD

中介轴承作为双转子系统高低压转子重要的支承部件,其内圈和外圈均随着低压转子和高压转子高速旋转,其传热问题更加突出.本文研究中介轴承在非线性动载荷作用下的非线性热行为.基于双转子系统动力学响应定义中介轴承动载荷,考虑中介轴承的径向游隙、分数指数非线性和参数激励等非线性因素,中介轴承动载荷会出现跳跃和双稳态等非线性行为.考虑润滑剂的黏温关系,根据Palmgren经验公式建立动载荷作用下中介轴承的热传递模型,通过数值求解得到中介轴承稳态温度,发现动载荷的非线性行为导致中介轴承温度出现跳跃和双稳态等非线性热行为.分析转速比、偏心距、中介轴承径向游隙、Hertz接触刚度和滚子数目对中介轴承温度及非线性热行为的影响,表明偏心距、径向游隙和刚度只影响非线性热行为,而转速比和滚子数目对两者都有重要影响.本文研究表明,动载荷相较于静载荷更适合描述中介轴承的实际载荷,由于双转子系统具有非线性振动特性,中介轴承的热行为也表现出复杂的非线性行为.

As an important supporting part between the higher pressure rotor and the lower pressure rotor in a dualrotor system,inner and outer races are rotating with the lower and higher pressure rotors,the heat transfer of the intershaft bearing is more prominent.This paper studies the nonlinear thermal behaviors of the inter-shaft bearing under the nonlinear dynamic load.The dynamic load of the inter-shaft bearing is defined based on the dynamic responses of the dual-rotor system,where the nonlinear factors of the inter-shaft bearing such as the radial clearance,the fractional exponential nonlinearity and the parameter excitation are taken into consideration.Thus the nonlinear behaviors such as the jump and the bi-stable phenomena happen to the dynamic load.According to Palmgren’s empirical formula,a heat transfer model of the inter-shaft bearing under the dynamic load is established with considering the viscosity-temperature relationship of the lubricant.Steady-state temperatures of the inter-shaft bearing are obtained by the numerical integration.It shows that the nonlinear thermal behaviors of the inter-shaft bearing such as the jump and the bi-stable phenomena are caused by the nonlinear behaviors of the dynamic load.Furthermore,effects of the rotation speed ratio,the unbalances,the inter-shaft bearing’s radial clearance,Hertz contact stiffness and roller number on the temperatures and the nonlinear thermal behaviors of the inter-shaft bearing are analyzed.The results show that the unbalances,the radial clearance and the stiffness only affect the nonlinear thermal behaviors of the inter-shaft bearing;the rotation speed ratio and the roller number have a magnificent influence on both.This discovery implies that the dynamic load is more appropriate to describe the actual load of the inter-shaft bearing than the static load.The thermal behaviors of the inter-shaft bearing become nonlinear,which is much more complicated than before,due to nonlinear dynamic characteristics of the dual-rotor system.