Radially Floating Heat Shield for Gas Turbine Vane Thermal Expansion

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Solution Overview

Problem

Gas turbine engines face challenges in maintaining the integrity and lifecycle of turbine section components due to excessive heating from hot gases, which can reduce the effectiveness and lifespan of the casing and supporting structures.

Innovation Solution

A radially floating heat shield is coupled to the carrier of the blade track or segment, maintaining contact as the vane thermally expands and contracts, forming radial and axial seals to inhibit hot gas leakage and using secondary air or gas pressure to secure the heat shield against the blade track carrier, thereby protecting the casing from excessive heat.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a heat shield is used to protect the casing from hot gases, then the thermal protection and structural integrity are improved, but the device complexity increases

Engineering Contradiction:

Improvethermal protectionVSAvoiddevice complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The heat shield is divided into multiple segments that can move independently relative to each other, allowing the structure to accommodate thermal expansion and contraction while maintaining sealing effectiveness. This segmentation enables the heat shield to adapt to dimensional changes without compromising the overall protective function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The heat shield incorporates movable joints and flexible connections that allow it to dynamically adjust its position and configuration in response to thermal cycling. This dynamic capability enables the heat shield to maintain contact and sealing effectiveness throughout the full range of thermal expansion and contraction.

Inventive Principle:

Principle #15Dynamics

2Reliability

If the heat shield is made rigid to maintain sealing effectiveness, then the seal reliability is improved, but the adaptability to thermal expansion and contraction deteriorates

Engineering Contradiction:

Improveseal reliabilityVSAvoidadaptability to thermal expansion

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The heat shield utilizes flexible membrane structures and thin-walled components that can deform elastically to accommodate dimensional changes. These flexible elements maintain sealing effectiveness through continuous contact while adapting to the full range of thermal expansion and contraction cycles.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The heat shield design explicitly accounts for thermal expansion by incorporating expansion joints, clearance gaps, and compliant mounting structures. These features allow the heat shield and surrounding components to expand and contract freely while maintaining effective sealing contact throughout the thermal cycle.

Inventive Principle:

Principle #37Thermal expansion

3Reliability

If the heat shield is designed to float radially to maintain contact during thermal expansion, then the seal effectiveness is improved, but the manufacturing precision requirements increase

Engineering Contradiction:

Improveseal effectivenessVSAvoidmanufacturing precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The heat shield employs self-adjusting mechanisms such as spring-loaded contacts, gravity-assisted positioning, and pressure-equalization features that automatically maintain optimal sealing contact. These self-service features compensate for manufacturing tolerances and ensure reliable sealing without requiring ultra-precise manufacturing.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The heat shield design incorporates adjustable parameters such as clearance gaps, contact pressures, and positioning tolerances that can be optimized during assembly and operation. These adjustable parameters allow for compensation of manufacturing variations and ensure effective sealing across different production batches.

Inventive Principle:

Principle #35Parameter changes

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 heat shield effectively reduces thermal stress on the turbine section components by forming seals that prevent hot gas leakage, enhancing the structural integrity and lifespan of the engine components while optimizing performance and reducing fuel consumption.

Implementation Method 1

maintaining contact as the vane thermally expands and contracts

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

Secondary air from the vane direction or hot gases from the turbine blade may push the heat shield in a longitudinal direction against the blade track carrier

Methodology Applied

Scientific EffectPressure: Pressure Increase

Data Source

PatentUS10428689B2Heat shield for a gas turbine engine

Publication Date: 2019.10.01 ROLLS ROYCE DEUT LTD & CO KG

AI summary

A subassembly of a gas turbine engine includes a heat shield and carrier subassembly for a turbine section are disclosed. The carrier includes support features to couple to an engine casing. The upstream end of the carrier includes a radially inward arm extending toward to an engine axis. The outer end of the radially floating heat shield is coupled to the radially inward arm via a pin-and-slot joint configured to allow movement of the heat shield relative to the radially inward arm of the carrier. In response to thermal expansion and contraction of the vane, the heat shield is configured to move radially outward and inward, respectively, relative to the radially inward arm to maintain contact with the outer platform of the vane.