Lubrication Characteristics And Temperature Field Of Water Lubricated Rubber Bearings

Water-lubricated rubber bearings have been widely used with the improvement of the awareness of saving and environmental protection.However,most of its research focuses on experimental methods,resulting in a single measurement point,and it is impossible to obtain the complete water film pressure,thickness,temperature and other important parameters of the bearing.Based on the theory of hydrodynamic pressure and computational fluid dynamics,this paper uses FORTRAN language to compile and build water-lubricated bearings without grooves,numerical calculation models for water-lubricated bearings with grooves,and CFD models for water-lubricated bearings with FLUENT software.The influence of eccentricity,radius clearance,shaft speed,water temperature,groove number and groove type on bearing lubrication characteristics and temperature field is discussed.The main work and conclusions are as follows:(1).Researched non-groove bearings,the increase in eccentricity,the decrease in the radius clearance,the increase in the speed of the stern shaft and the decrease in the temperature of the water medium can all increase the water film pressure,especially when the eccentricity exceeds 0.7 and the radius clearance is less than 1.1mm,the increase in pressure gets bigger,but the increase change caused by the eccentricity is more obvious,the increase of the stern shaft speed will also increase the pressure increase of the water film,and the pressure increase caused by the temperature of the water medium is basically stable.;the increase of the eccentricity and the decrease of the radius gap can make the smallest film The thickness decreases,but the increase in eccentricity will increase the maximum film thickness.The effect of the radius gap is opposite to that.The stern shaft speed and the temperature of the water medium have no effect on the film thickness.In addition,with the changes of these four parameters,the bearing capacity will increase and the friction coefficient will decrease.When the eccentricity and the radius gap are constant,The speed of the stern shaft has the greatest influence on the friction coefficient and the bearing capacity,while the temperature of the water medium has a stable influence on the bearing capacity and the friction coefficient,and there will be no sudden changes in numerical values.(2).Researched grooved bearings,when the number of grooves is constant,the influence of eccentricity,radius clearance and stern shaft speed on the water film pressure and thickness is basically similar to that of non-grooved bearings.Because the existence of grooves is considered,There is a pressure peak in each bearing area,and the larger the circumferential angle,the greater the pressure peak in the bearing area.Middle section in the width direction of the bearing,that is,the Y=0 secti’on,the maximum pressure peak moves toward the main bearing area with the increase of eccentricity and finally stabilizes here,the pressure value increases rapidly.At the same time,the maximum pressure section in the axial direction,that is,the θmax section,unlike the arc-shaped pressure curve of a non-groove bearing,a pressure plateau with almost constant pressure value appears in the pressure curve.Finally the number of grooves has a great influence on the bearing capacity and friction coefficient,when the bearing capacity is increased from 6-slot bearing to 10-slot bearing,the bearing capacity decreases by 32%and 31%,while the friction coefficient increases by 53%and 50%,respectively.Under the same conditions,it is nearly 20 times the friction coefficient of a non-groove bearing.(3).Researched different groove types,when the number of grooves is constant,on the entire water film pressure surface,the water film pressure of the V-groove bearing is the largest,and the rectangular groove bearing is the smallest.At the same time,it will be in the secondary load-bearing areas after the main load-bearing area.A sharp pressure peak appears in the inlet area.The larger the circumferential angle of the secondary bearing area,the smaller the pressure peak.In addition,the pressure peak is most affected by the speed of the stern shaft,followed by the radius clearance,and the number of grooves has no effect on it.Secondly,the increase in the number of grooves will cause the maximum pressure peak stable position to move toward a higher eccentricity.Finally,under the same structure and working parameters,the V-slot bearing has the largest bearing capacity and the smallest straight groove;at the same time,when the eccentricity is less than 0.6,the friction coefficient of the V-slot bearing is the smallest,followed by the T-slot bearing,the rectangular groove is the largest,and the groove is the largest.The increase in the number of slots does not affect this law.(4).Researched the temperature field of the water film,the heat flux value applied to the inner wall of the water film and the composite flow rate of the water medium on the bearing working surface are the decisive factors.At the initial stage when the inlet velocity of the water medium increases,the temperature of the water film decreases significantly,but if the flow velocity continues to increase,the marginal value of the influence on the temperature gradually decreases.The increase of the eccentricity will result in a smaller heat flux density,and the area occupied by the local high temperature area of the water film will be significantly reduced.The increase of the stern shaft speed will increase the heat flux density,but it can take away more heat.Therefore,there is a critical speed.When the speed is less than critical speed,the increase of the speed will only increase the maximum temperature of the water film and cross this critical speed.After the value,the maximum temperature of the water film will drop instead.Finally,the V-groove bearing has the lowest heat flux density and the fastest synthetic speed,so it has the smallest water film maximum temperature.The heat flux value of the T-slot bearing and the straight groove bearing is similar to the synthetic flow velocity value,but the rectangular groove can hold more water and take it away.Therefore,the maximum temperature of straight groove bearings is lower than that of T groove bearings.