| Journal bearing is an important part of the large and heavy load rotating machinery such as steam turbine, gas turbine and compressor. It relies on high viscosity lubricating liquid which under load of rotor formed between the journal and bearing convergence broaden wedge gap in the flow of medium, providing lubrication between dynamic and static surface, transfering the heat generated by the friction rotor. The static and dynamic characteristics and macroscopic characteristics of journal bearing friction power consumption directly affects the safe and stable operation of the equipment. The flow state and structure of the lubricant in the gap is the physical basis of the macroscopic characteristics, which plays a decisive role. The lubricat oil will produce the oil film force in the bearing,which can also be coupled with the motion of the rotor,and the combination has an important influence on the motion stability of the rotor system. In this paper, we study some basic properties of the lubricating oil, and carry out the numerical simulation of the journal bearing.The paper adopts combine theory and practice, we study the method of lubricating oil gas content measurement, and two influence factors of lubricating oil gas content which are temperature, back pressure.And we find the lubricating oil gas content has an influence on viscosity. We also study the connection between lubricating oil viscosity and temperature. Based on the experimental results, we study the influence of the viscosity of lubricating oil on the flow characteristics of the journal bearing.In the experiment aspect, a new method to measure the gas content of lubricating oil is put forward, and apply for a patent. With this method, the gas content of lubricating oil is obtained and its connection with temperature, back pressure is studied.At the same time we study he lubricating oil gas content has influence on viscosity. By using Brookfield DV2T viscometer, we measure different kinds of lubricating oil at different temperature viscosity, the data were linear processing. We find that the higher the temperature, the smaller the viscosity.The data accord with the Walthcr formula.We calculation the corresponding coefficient, and make the basic work for the follow-up of the dynamic characteristics of the journal bearing.On the theoretical aspect, The influence factors of the static characteristics of the sliding bearing are analyzed by studying the Reynolds equation.We use the experimental data and formulas, according to the temperature field distribution in the bearing, we fit the distribution of viscosity in the bearing, and solve the pressure field of the bearing. By comparison effective temperature method, consider the change of circumferential temperature method, take into account the temperature change in two directions of circumferential and axial directions method.We find that the finite difference method is more accurate, and consider two directions is more able to complete the description of the journal bearing within the distribution of the situation.Through experimental and theoretical studies,we find that,The gas content of lubricating oil decreases with increasing pressure,and with the increase of the temperature of lubricating oil, the trend of first increase and then decrease. And at the same temperature and back pressure, we find that with the increase of the gas content of lubricating oil, the viscosity will become smaller. It shows that the viscosity of the lubricating oil is in accordance with the Walther formula. The corresponding coefficient of the lubricating oil is obtained. Based on the original Reynolds equation, the viscosity of the derivation is considered, and we obtain the generalized Reynolds equation. We find the finite difference method used to solve the numerical solution is more accurate. Finally, through the MATLAB programm, in three different temperature conditions, we get the related dynamic characteristics of journal bearing. |
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