Optimization Design of Liquid Metal Lubricated Thrust Bearing in X-Ray Tube for High Speed Computed Tomography

The high temperature, high vacuum and high rotational speed working environment of high speed Computed Tomography (usually abbreviated as CT) X-ray tube puts forward strict requirements for the lubrication design of its rotating anode. The excellent thermal conductivity, flowability and thermal stability of liquid metal alloy (gallium indium tin) make it the best choice for CT X-ray tube lubricants. However, the sealing issues of the liquid metal alloy are particularly important. This paper focuses on the optimization design of the liquid metal lubricated herringbone groove thrust bearing. Firstly, the coordinate system of the spiral groove region is transformed into a sector region coordinate system based on boundary fitting, and the dimensionless Reynolds equation after coordinate transformation is derived. Then, the Reynolds equation is discretization solved by MATLAB based on the finite difference method. At the same time, FLUENT is used for fluid simulation of the thrust bearing, and the simulation results are verified with MATLAB calculation results. The range of error between two simulation calculation methods is approximately 4–6%. To obtain the sealing characteristics of the thrust bearing, the liquid metal lubricating film pressure of the thrust bearing system in the working environment is analyzed first. Then, the leakage and load carrying capacity are studied. Taking leakage and load carrying capacity as the main indicators, the optimization design is carried out by comprehensively considering the depth, numbers, width ratio, and helix angle of the herringbone groove thrust bearing.