Tapered Multi-Film Oil Damper Rings to Prevent Ring Sticking

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Solution Overview

Problem

Multi-film oil dampers in the gas turbine industry face challenges in distributing oil effectively between nested damper rings due to air voids and surface tension, leading to inadequate oil flow and coating, which impede the damping performance, especially under high rotor imbalance conditions.

Innovation Solution

A multi-film oil damper design with a housing, closure ring, and coaxially nested damper rings, where the axial end surfaces of the rings create a wedge gap to allow oil pressure to separate the rings, ensuring proper oil distribution and coating by applying pressurized oil to the spaced apart axial ends, facilitating radial movement and damping.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple nested damper rings are used to increase damping capacity, then the radial damping movement capacity is improved, but the oil distribution between rings deteriorates due to air voids and surface tension

Engineering Contradiction:

Improvedamping performanceVSAvoidoil flow distribution

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The damper rings are segmented with non-circular cross-sections featuring flattened portions and rounded portions, creating distinct axial end surfaces that facilitate oil distribution. This segmentation allows each ring to have optimized geometry for both damping function and oil flow characteristics.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The closure ring acts as an intermediary component that actively manages oil distribution between the nested damper rings. It includes features like radially inwardly extending portions and axial end surfaces that direct pressurized oil to separated ring interfaces, overcoming the surface tension barrier.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a thin layer of liquid oil is maintained between adjacent damper rings, then the damping function is preserved, but the separation of damper rings deteriorates due to liquid surface tension

Engineering Contradiction:

Improvedamping functionVSAvoidring separation distance

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The damper rings employ asymmetric cross-sections with flattened portions and rounded portions, creating unequal axial end surface geometries. This asymmetry generates pressure differentials that overcome surface tension forces, enabling sufficient ring separation while maintaining the necessary thin oil film for damping.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The invention changes the geometric parameters of the damper rings by introducing non-circular cross-sections with specific flattened and rounded portions. This parameter modification alters the pressure distribution and oil film characteristics, enabling both ring separation and adequate oil coating.

Inventive Principle:

Principle #35Parameter changes

3Quantity of substance

If pressurized oil is applied to separate damper rings, then the oil distribution is improved, but the device complexity increases due to additional structural features

Engineering Contradiction:

Improveoil distributionVSAvoiddamper ring structure

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The closure ring serves multiple functions: it seals the damper cavity, distributes pressurized oil to the damper rings, and provides structural support. The flattened and rounded portions of the rings simultaneously influence oil flow patterns and structural integrity, reducing the need for separate components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 ensures reliable oil distribution and coating between damper rings, enhancing the damping performance by preventing ring sticking and ensuring sufficient oil flow, even under conditions of rotor imbalance, thereby improving the overall functionality of the oil damper.

Implementation Method 1

The oil film damper is supplied with oil from an oil supply inlet, often in the outer diameter of the damper cavity... injecting pressurized oil into the oil damper cavity via an oil inlet... applying oil pressure on the spaced apart adjacent axial end surfaces

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

a thin layer of liquid oil between adjacent damper rings can impede separating the damper rings due to the attractive force of liquid surface tension

Methodology Applied

Scientific EffectSurface tension: Surface Tension

Implementation Method 3

Squeeze film oil dampers with a single oil film are well known and used throughout the gas turbine and turbomachinery industry... provide damping to a rotor system to reduce vibrations

Methodology Applied

Scientific EffectViscous damping: Viscous Damping

Data Source

PatentUS11067121B2Multi-film oil damper with tapered damper rings

Publication Date: 2021.07.20 PRATT & WHITNEY CANADA CORP

AI summary

A multi-film oil damper has a housing defining an annular damper cavity between a radially outward wall and radially extending side walls. The annular damper cavity has an oil inlet configured for connection to a source of pressurized oil. A closure ring defines a radially inward boundary of the annular damper cavity. First and second damper rings are nested together coaxially within the annular damper cavity. At least one of the first damper ring and the second damper ring has an axial end radial thickness less than an intermediate-portion radial thickness.