A Study the Axial and Radial Rotor Stability of the Turbo Machinery with Allowance the Geometry of the Surface and Properties of the Lubricating Fluid

Abstract

An ensuring of the axial and radial rotor stability is one of the main objectives in the design and operation of the small-sized turbo-machinery. Hydrodynamic thrust bearings must securely restrain unbalanced axial forces, arising during any possible operating modes. Using of the different types of intermediate elements provides a stable position of the rotor in the radial bearings. Recently flexible rotors have been widely used in small-sized turbo-machines. The complexity of the implementation of methods for calculating the dynamics of these rotors is to solve a system of motion equations. The system of motion equations, which is presented in this work, contains the motion equation for the each bearing element, including the floating rings and elements of the rotor (wheels of the turbine and compressor, the central mass). The load acting on the bearings includes the masses of elements, the reaction of lubricating layers and the rotor imbalance, potential impact loads and forces torques, acting on the rotor from the other elements of the rotor. To calculate the reactions of lubricating layers for two-layer bearings the hydrodynamic pressure field and the friction losses were considered for a real bearing design, on the surface of which the sources of the lubrication is always located. The thrust bearings with segments of various designs have been considered, including laser texturing surface. The trajectories of the rotor elements of the turbo-machinery for various rotation velocities, as well as the elastic line of the rotor at different time points are represented as the results of the calculation.

Keywords

• Flexible rotor
• Journal bearing
• Thrust bearing
• Hydro-mechanical characteristics
• Load-capacity