Bearing Calculation and Analysis Capabilities – AxSTREAM®
Introduction
Rotor dynamics analysis would neither be complete nor reliable without accurate modeling of bearings. The AxSTREAM Bearing™ module is used to determine hydrodynamic and mechanical characteristics for different types of hydrodynamic journal and thrust bearings as well as auxiliary component characteristics such as seals, squeeze film dampers, etc.
The AxSTREAM Bearing™ module enables users to analyze hydrodynamic bearings of the following types:
- Journal Hydrodynamic Bearing Types
- Plain Cylindrical
- Fixed Pad (including Elliptical Type)
- Tilting pad
- Thrust Hydrodynamic Bearing Types
- Fixed Pad
- Tilting Pad
- Gas Foil Bump Bearing
- Bump foil
- Spiral groove
Additionally, the following can also be calculated in AxSTREAM Bearing™:
- Hydrostatic Bearings
- Rolling Element Bearings (utilizes radial stiffness as a parameter)
- Deep Groove
- Self-Aligning
- Spherical Roller
- Straight Roller
- Tapered Roller
- Auxiliary Component Simulation
- Squeeze Film Dampers (stiffness & damping equivalent characteristics)
- Liquid and Gas Seals (stiffness, damping, mass equivalent characteristics)
- Aerodynamic Cross-coupling
The embedded library of fluids allows users to use new or existing incompressible and compressible fluids throughout different projects while accounting for temperature-dependent properties and heat transfer with housing and journal.
Analysis & Post-Processing
Several analyses using Finite Difference Method (FDM) can be performed in this module:
- Steady state – Performed for the bearing under static loading in order to determine the equilibrium position at a constant rotational speed. The following characteristics are computed under steady state analysis:
- Pressure distribution
- Friction coefficient
- Friction power loss
- Flow Rate
- Oil Temperature Increment
- Minimum Oil Film-Thickness
- Temperature distribution
- Eccentricity and Angle
- Fractional Film Content
- Sommerfeld number
- Critical Mass
- Mechanical characteristics: Stiffness and Damping coefficients
- Whirl stability – Simulates shaft motion trajectory as a result of perturbation. The initial parameters, load on bearing, unbalance value and rotational speed are used here. In addition, journal orbits can be estimated relative to the bearing’s inner surface as the result of the analysis.
- Bearing map analysis –Series of steady-state analyses calculated for different rotational speeds. The results are same with steady state analysis, but calculated for each speed in the range which was set up. The calculated stiffness and damping map characteristics are used rotor dynamics analysis.
These properties can then be exported to a printer-friendly report or the AxSTREAM® RotorDynamics software in order to automatically use the appropriate values during rotor dynamics analyses. Additionally, pockets, misalignments, etc. can be considered for the different calculations.
Moreover, the lubricant flow rate is calculated along with the heat balance and temperature distributions.
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