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Bearing oil film damping force of inertia

Author: LiQiChao
Tutor: TanQingChang
School: Jilin University
Course: Mechanical Design and Theory
Keywords: Fluid inertia Damping bearings Oil film force
CLC: TH133.3
Type: Master's thesis
Year: 2011
Downloads: 70
Quote: 0
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Abstract

Reduced weight of the shaft and the elastic support is to increase the shaft speed to achieve a supercritical state machine The main technical way. Because damping bearing has good damping capacity, high-speed shaft bearing system in a variety of additional damping devices, the most widely. In the high speed rotor - bearing system (referred shafting) kinetic design, bearing Hydrodynamic damping parameter is calculated speed shaft stability margin, critical speed and unbalance response of the basic parameters. The continuous improvement of the machine operating speed and low viscosity oil has made the fluid inertia Hydrodynamic characteristics produced more and more significant role. Practice has proved that in this case, the analysis film of fluid dynamic parameters to be considered the effect of inertia. This raises the fluid inertia in considering, under the premise of the bearing oil film dynamic characteristics of the proposition. Hydrodynamic Navier-Stokes equations (abbreviated N-S equations) shows that the velocity distribution of the oil film bearing oil film is to study the dynamic behavior of the theoretical basis. Based on the inertia of the fluid-containing N-S equations to study the velocity distribution of fluid inertia on the film role, according to the Navier-Stocks equations to establish a squeeze film damping bearing oil inertial velocity distribution model, and apply the alternating direction implicit difference method and self-emulation program for the preparation of a set of numerical calculation, successful use of technology to solve a linear iterative N-S equations nonlinear problems, establish a short film bearing inertial velocity distribution. This distribution reflects the fluid inertia on the film Speed. The results show that the damping rate of the radial bearing oil film inertia significantly parabolic distribution. When Reynolds little (less than 8), eccentricity little (less than 0.35), the fluid inertia with Reynolds and the increase of eccentricity, the greater its value the faster the rate of increase, the traditional assumption is no longer reasonable. Permit calculation of the time step had increased to 0.006 when the calculation still has good stability and convergence. And the convergence velocity with time step increases rapidly accelerated. Thus the difference method derived herein algorithm stability and convergence indicators (growth factor is less than 1) coincide. Based on N-S equations, this non-traditional inertial solution, there is inertia solution for theoretical research, while these two analytical and numerical solutions for comparative analysis proved. According inertial velocity distribution, we study the fluid inertia effect on Hydrodynamic parameters. Progress of this work is to fill the gap between the largest of the traditional theory of fluid inertia on the film ignored the impact of the shortcomings of the velocity distribution, the development of a new short film bearing dynamic parameters of the model. Experimental results show that the new model is obviously superior to the conventional damping force bearing film theory, especially for film damping force theory improvements. In theory, the new model reflects the film damper force non-linear relationship with the oil viscosity to solve large Reynolds traditional theory and experimental results when the conflict between. The use of inertial velocity distribution of the research work also demonstrated in the large Reynolds number, the traditional theory of the non-inertial velocity dependent distribution hypothesis (ie ignoring fluid inertia caused by changes in the distribution of the film speed premise of fluid inertia Hydrodynamic Parameters) is unreasonable, it will Hydrodynamic analysis parameters cause large errors. In this paper, the circumference of the damping bearings often precession, according to the three-dimensional N-S equations establishes a fluid inertia improvements including Reynolds equation. Reynolds equation using improved study the dynamic characteristics of the short film bearing established Hydrodynamic parameters of the mathematical model. The experimental results and numerical analysis shows that the results obtained are correct. Analysis of the dynamic characteristics of the bearing oil film explores a new way.

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CLC: > Industrial Technology > Machinery and Instrument Industry > Mechanical parts and gear > Moving parts > Bearing
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