Авіаційно-космічна техніка та технологія (Jun 2022)
Analysis of the operation of thrust bearings of turbomachines on environmentally adaptive lubricant
Abstract
The subject of study in this article is the cost-effectiveness of the rotors of powerful turbines and their fire safety. Improvement of these indicators is possible by replacing oil lubrication systems with environmentally adaptive lubricants (EAL), in particular water or aqueous solutions. The main disadvantage of using water and other low-viscosity aqueous solutions for operating plain bearings is the lack of a hydrodynamic effect at low speeds of the rotor during start and stop of the turbine. The current study experimentally studies the possibility of replacing oil lubrication systems with EAL, in particular water or aqueous solutions. The objectives of the study: 1) to ensure that in the operating range of speeds and loads, the bearing operates in a stable hydrodynamic mode; 2) show that the use of a hydrostatic lifting system provides a liquid mode of friction in the range under study of loads and sliding speeds; 3) to determine the level of pressures at which the rotor rises. When solving this problem, the following methods were used. On the experimental stand, a full-scale radial bearing with babbitt filling of the working surface of the liner was tested. During the experiment, the following parameters were varied and measured: rotor speed, bearing load, lubricant consumption, working fluid temperature in front of and out of the bearing, water pressure (condensate) in the hydraulic system, pressure in the lubricating layer and chambers of the bearing. The main parameter by which the efficiency of the bearing was evaluated was the thickness of the lubricating layer of the working fluid. The following results were obtained. In the first stage, when the speed of the rotor is zero, the value of the pressure of the fluid supply, which ensures the emergence of the shaft. In the second stage, the dependence of the relative eccentricity on the shaft speed and the speed at which it is possible to turn off the rotor lifting system. Conclusions. In the investigated range of speed and loads, the bearing operated in a stable hydrodynamic mode. The use of a hydrostatic lifting system provided a liquid mode of friction in the range under study of sliding speeds (including starting and stopping the rotor). The temperature of the working surface of the bearing in a stable hydrodynamic mode depends little on the external load and sliding speed.
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