Study of thermal processes in the turbocharger bearing housing for the efficiency and performance of tribounits

Engine building is one of the critically important branches of power engineering. The presence of a turbocharging unit in a modern engine allows it to meet high requirements for energy efficiency and environmental friendliness. At the same time, modern trends in the modernization of supercharging units are characterized by an increase in mechanical and thermal loads on turbocharger elements, including journal bearings. Hydromechanical characteristics, the analysis of which allows us to estimate the operability of journal bearings, depend on a large number of external and internal factors. The most significant are: the properties of the lubricant, the thermal load of the structural elements, as well as processes in the bearing housing. Taking into account the influence of these factors requires new numerical calculation methods, approaches to assessing the load-bearing capacity and other characteristics of tribounits. The main goal of this work is to determine the level of thermal loads arising in the elements of the bearing unit housing, as well as their effect on the dynamics of a flexible asymmetric rotor and the hydromechanical characteristics of tribounits. To conduct the computational studies, the algorithm of elastic rotor dynamics on multilayer journal bearings developed and tested by the authors was used. As the results of the studies, the paper presents the dependencies of the hydromechanical characteristics of multilayer journal bearings, as well as the values of the oscillation amplitudes of the flexible rotor elements under the influence of thermal processes. The operability of the journal bearings was assessed by the value of the oscillation amplitude of the compressor wheel nut. In this case, the values of the temperature of the structural elements and the lubricant in each layer of tribounits were taken into account. Based on the obtained results, it was revealed that the thermal processes occurring in the bearing housing during the operation of the mechanism significantly affect the characteristics of the journal bearings, which in turn ensure the operability of the turbocharger as a whole. In this regard, to select the geometric characteristics of the journal bearings at the design stage of the turbocharger, it is necessary to take into account both the speed modes and the thermal loads on the housing elements.