Lead-Lag Damper Conductive Cover for Rotor Hub Heat Dissipation

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Solution Overview

Problem

Fluid-elastic or hydraulic lead/lag dampers in rotorcraft rotor hubs generate significant heat that must be dissipated quickly to maintain performance, but insufficient airflow in fully covered rotor hubs impedes cooling, potentially leading to dangerous situations.

Innovation Solution

A conductive cover, such as a graphite polymer or graphene sheet, is wrapped around the exterior surface of the damper housing to facilitate heat dissipation by diffusing heat away from the heat-generating regions, utilizing materials with high thermal conductivity like Pyrolytic Graphite Sheets (PGS) to enhance cooling efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a rotor hub is completely covered by a rotor hub fairing, then aerodynamic efficiency is improved, but heat dissipation from dampers deteriorates

Engineering Contradiction:

Improveaerodynamic efficiencyVSAvoidheat dissipation

Core Design Contradiction:

Loss of energyVSTemperature

Solution Approach 1:

The fairing is segmented to include thermal management openings that allow heat dissipation pathways while maintaining aerodynamic coverage. The damper housing is segmented to include external heat dissipation fins that extend through the fairing structure, creating separate thermal channels independent of the aerodynamic envelope.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Thermal conductive materials are introduced as intermediaries between the damper housing and the fairing structure. These materials facilitate heat transfer from the damper to the fairing exterior, acting as a thermal bridge that allows heat dissipation without compromising the aerodynamic sealing of the fairing.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If airflow over dampers is increased for cooling, then heat dissipation is improved, but aerodynamic efficiency deteriorates

Engineering Contradiction:

Improveheat dissipationVSAvoidaerodynamic efficiency

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The fairing structure is designed with localized thermal management features at specific locations where dampers are mounted, rather than creating general airflow disruptions. Thermal conductive pathways are concentrated at damper contact points, allowing localized heat dissipation without affecting overall aerodynamic flow patterns.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Heat dissipation is moved from the aerodynamic flow dimension to the thermal conduction dimension. Instead of relying on convective cooling from airflow, the system uses conductive heat transfer through the fairing structure to a separate thermal management system, decoupling thermal and aerodynamic functions.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Temperature

If damper housing is exposed for cooling, then heat dissipation is improved, but protection from environmental factors deteriorates

Engineering Contradiction:

Improveheat dissipationVSAvoidenvironmental protection

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The fairing acts as an intermediary protective layer between the damper housing and environmental factors. Thermal conductive pathways are integrated into the fairing structure, allowing heat transfer while the fairing continues to provide protection from weather, debris, and other environmental hazards.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The fairing is designed as a flexible yet thermally conductive shell that can accommodate heat transfer pathways while maintaining environmental protection. Thin film thermal conductive materials are applied to the fairing interior surface, providing thermal pathways without compromising the protective enclosure.

Inventive Principle:

Principle #30Flexible shells and thin films

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 conductive cover effectively increases heat dissipation capabilities of lead/lag dampers, maintaining performance even in fully shrouded rotor hubs by efficiently diffusing heat away from thermally sensitive components, thereby preventing performance degradation and ensuring safety.

Implementation Method 1

a conductive cover wrapped around a portion of an exterior surface of the housing between the first attachment member and the second attachment member

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11554864B2Techniques for increasing heat dissipation in lead-lag dampers

Publication Date: 2023.01.17 TEXTRON INNOVATIONS INC

AI summary

One embodiment described herein is a damper for a rotor system, the damper comprising a cylindrical housing having a hollow interior; a piston disposed within the hollow interior and extending along a central axis of the housing; a first attachment member disposed on a first end of the damper and connected to the housing; a second attachment member disposed on a second end of the damper and connected to the piston; and a conductive cover wrapped around a portion of an exterior surface of the housing between the first attachment member and the second attachment member.