Sorokina T. Improving the method for calculation and design of hybrid thrust bearings

The dissertation is dedicated to the solving the scientific and technical problem – improving the method for calculation and design of hybrid thrust bearings, which takes into account, unlike the previous researchers, the formation of lubricant turbulence and temperature conditions in the lubricating layer. Modern design schemes and operating conditions of different types of sliding liquid friction thrust bearings have been carried out. The sphere of application of sliding liquid friction hybrid thrust bearings as a part of the bearing unit is considered. The review of calculation methods for sliding liquid friction hybrid thrust bearings is given. On the basis of the analysis, a finite-difference method was chosen to make operating characteristics calculations for the hybrid thrust bearings. The analysis of equations for calculating the operating characteristics of this bearing is carried out. The basic equations of the thermohydrodynamic lubrication theory of hybrid thrust bearings under the lubricant turbulent motion were chosen according with the turbulent model V. N. Konstantinescu. The solution of these equations is numerically solved by the method of finite differences with the template of the explicit scheme "cross" and was reduced to the solution of the system of algebraic equations with respect to pressure and temperature. The system of algebraic equations was solved by an iterative method – the method of upper relaxation. On the basis of the equations of the thermohydrodynamic lubrication theory and selected methods a mathemetical model and computer program for calculating the operating characteristics of the hybrid thrust bearing is worked out. The theoretical calculations and curves of load capacity, power losses due to friction lubricant consumption and the maximum temperature of the hybrid thrust bearings with Raleigh pocket lubricating layer are performed. The regularities of change in operating characteristics of this types of bearings due to the formation of turbulence in the bearing lubricant layer between the pad bearing and collar, which leads to a change the layer’s pressure and temperature is obtained. It was established that the rational choice of the lubricant supply pressure and geometric parameters of the hybrid thrust bearing can increase the load capacity of this bearings in 1.1...1.35 times and to reduce the power loss due by a friction on 20...46 %. The performed analysis of the influence of the physical properties of oil on the hybrid thrust bearing operating characteristics showed that the using low viscosity oils allowed the best results to ensure the temperature regime of the oil layer. A comparative analysis of hydrostatic and hybrid thrust bearings usage in the bearing unit is conducted. On the basis of the analysis of the obtained performance curves for both types of bearings, it was concluded that the hybrid thrust bearing is advisable. Test bench has been modernized for conducting experimental researches of the working characteristics of the experimental sample of the bearing at different operating modes. The experimental sample of the hybrid thrust bearing was designed and manufactured. The analysis of the equipment and means of measurement for control the experimental sample performance characteristics are carried out. A description of the automated complex for measuring and processing of sensor parameters during the tests is given. The experimental technique of hybrid thrust bearing working characteristics on different operating modes is carried out. Experimental and theoretical tests of hybrid thrust bearing are carried out. Comparative analysis of the obtained research of bearing capacity, the temperature state of the lubricant in the lubricating layer, lubrication consumption and power losses to friction are presented. It is shown that the theory and experiment are in good agreement with each other. The error in the determination of the carrying capacity does not exceed 5 %, the difference in lubricant temperature does not exceed 1...2°С. Manufactoring feasibility report of designed hybrid thrust bearing is determined. It’s shown that it manufacturing cost is not significantly different from the cost of the hydrostatic bearing. Presented research technique of the improvement of the hybrid thrust bearings calculation and design method, tables and graphs of bearings performance characteristics, depending on the design parameters, simplify the process of their design, which has an important practical significance. The results were proved under the state enterprise Gas Turbine Research and Production complex «Zorya»-«Mashproekt».