Self-Pressurizing Hydrodynamic Bearing for Rotary Machines
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Solution Overview
Problem
Rotary machines face significant challenges with axial thrust, axial oscillations, and radial oscillations, which affect their reliability and efficiency due to factors like wear in rotor seals and fluid dynamics, leading to premature bearing failure and instability.
Innovation Solution
A self-pressurizing hydrodynamic or aerodynamic bearing system is created using a stationary subdividing disc and a rotor, with peripheral vanes and restrictive means to alter flow dynamics, reducing axial thrust and radial oscillations by redirecting leakage flows and increasing pressure, thereby improving rotor stability and positioning precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rotor seal designs are used, then the machine can operate, but axial thrust increases and bearing reliability decreases due to leakage flow and pressure changes
Solution Approach 1:
The rotor seal is segmented into multiple restrictive means areas (first, second, third restrictive means) distributed around the periphery, each contributing to pressure control. This segmentation allows better management of leakage flow and pressure distribution, reducing axial thrust while maintaining reliability
Solution Approach 2:
A pre-dam area is introduced as an intermediary zone between the restrictive means and the dam area. This pre-dam area gradually builds up pressure before the main dam, creating a more controlled pressure transition that reduces axial thrust on the bearing
2Duration of action of moving object
If rotor seals wear out, then the machine continues to operate, but annular gap leakage flow increases causing higher axial thrust and premature bearing failure
Solution Approach 1:
The design incorporates a pre-dam area that acts as a cushioning zone before the main dam. This pre-dam area gradually increases pressure in advance, compensating for wear in the rotor seals and maintaining pressure control throughout the operational life, preventing sudden increases in axial thrust
Solution Approach 2:
The pressure distribution parameters are changed by introducing multiple restrictive means and a pre-dam area. This creates a progressive pressure build-up mechanism that adapts to seal wear over time, maintaining acceptable axial thrust levels throughout the operational life
3Force
If axial thrust bearings are designed to handle high loads, then they can support the rotor, but the complexity and cost of maintenance increases
Solution Approach 1:
The invention converts the harmful leakage flow that causes axial thrust into a beneficial pressure-building mechanism. The leakage flow through the restrictive means and pre-dam area creates controlled pressure zones that actually reduce the net axial thrust on the bearing, allowing simpler bearing designs
Solution Approach 2:
The rotor seal system with multiple restrictive means and pre-dam area creates a self-regulating pressure distribution that automatically compensates for operating conditions. This self-service mechanism reduces axial thrust without requiring complex external control systems or high-capacity bearings
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces axial thrust and radial oscillations, enhancing the reliability and efficiency of rotary machines by minimizing the impact of wear and fluid-induced instability, allowing for closer tolerance seals and increased operational stability across a wide range of parameters.
Implementation Method 1
A self-pressurizing hydrodynamic or aerodynamic bearing system is created using a stationary subdividing disc and a rotor, with peripheral vanes and restrictive means to alter flow dynamics
Implementation Method 2
reducing axial thrust and radial oscillations by redirecting leakage flows and increasing pressure
Implementation Method 3
for the purpose of changing the nature of the flow dynamics and the pressure distribution along the outside of the rotor
Data Source
AI summary
A method and apparatus to reduce the axial thrust in rotary machines such as compressors, centrifugal pumps, turbines, etc. includes providing additional peripheral restrictive means (7) attached at the peripheral portion of the disk forming the subdividing means (4) on the side facing the rotating rotor (2). An additional ring element at the periphery of the subdividing means forms additional radial (11) and axial restrictive means (15). Such peripheral restrictive means (7, 11 and 15) function as sealing dams, which combined with the outward flow induced by the rotating impeller, form self-pressurizing hydrodynamic bearings in the axial and radial planes, improving rotordynamic stability. Additionally, a stationary ring element in the center of the cavity forms a seal with the rotor, reducing leakage to suction.