Turbine Blade Clearance Control via Segmented Thermal Expansion

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Solution Overview

Problem

Existing technologies fail to effectively control the clearance between rotating blades and stationary ring assemblies in gas turbines, particularly in a way that allows for localized thermal expansion or contraction without affecting surrounding parts, and are not suitable for compact designs or cold test bench applications.

Innovation Solution

A clearance controlling device comprising a shroud supporting rings, abradable ring sectors, elastic means, and temperature varying means, where the elastic means are positioned between the shroud supporting rings and abradable ring sectors, allowing for compact and efficient thermal regulation, with a high thermal expansion coefficient shroud and sectorized compression strips, and optional coolant fluid supply for precise temperature control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If air cooling of the bosses on the external annular case is used to vary the diameter of the stationary ring assembly, then the clearance between rotating blades and stationary ring assembly can be controlled, but thermal expansions or retractions affect surrounding parts including those of another stage

Engineering Contradiction:

Improveclearance control at blade topsVSAvoidthermal impact on surrounding parts

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The stationary ring assembly is segmented into a first stationary ring assembly and a second stationary ring assembly, allowing independent thermal control of each segment. This enables localized clearance adjustment at a specific turbine stage without thermally affecting adjacent stages, resolving the contradiction between clearance control precision and thermal impact on surrounding parts.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local thermal expansion control by providing separate cooling systems for different stationary ring assemblies. Each ring assembly can be independently cooled to achieve the desired clearance at its location, creating local quality changes that prevent widespread thermal impact on surrounding components.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If a valve and ducts assembly is used to control air flow rate and temperature for thermal expansion control, then clearance can be varied according to turbine working speed, but the device complexity increases

Engineering Contradiction:

Improveclearance control according to working speedVSAvoidbox for controlling clearance

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The cooling system is designed to serve multiple functions: it controls clearance at the blade tops, cools the stationary ring assemblies, and adapts to different turbine working speeds. This multi-functionality reduces the need for separate specialized components, thereby simplifying the overall device complexity while maintaining adaptability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Stability of the object's composition

If abradable ring sectors are attached to shroud supporting rings with elastic means, then the structure can accommodate thermal variations, but the device complexity and assembly difficulty increase

Engineering Contradiction:

Improvestructural accommodation of thermal variationsVSAvoidassembly structure with elastic means

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The elastic means are designed to change their mechanical properties (such as elasticity or rigidity) in response to temperature variations. This allows the structure to automatically accommodate thermal expansions or contractions without requiring complex adjustment mechanisms, thereby reducing device complexity while maintaining structural stability.

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

Enables precise control of clearance at the rotating blades' tops with minimal thermal impact on surrounding parts, achieving compactness and reliable operation across varying temperature gradients, suitable for both hot and cold test bench applications, and allowing for single-stage turbine installation without affecting adjacent stages.

Implementation Method 1

a shroud supporting abradable ring sectors inserted radially to the shroud supporting rings, between the elastic means and the abradable ring sectors which are attached to said shroud supporting abradable ring sectors, which has a volume varying according to temperature

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

means for varying the temperature of the shroud supporting abradable ring sectors and thus for varying the clearance (j) at the tops of the rotating blades

Methodology Applied

Scientific EffectTemperature variation:

Data Source

PatentUS10539037B2Device for controlling clearance at the tops of turbine rotating blades

Publication Date: 2020.01.21 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A device for controlling clearance at the tops of turbine rotating blades. The device comprises shroud supporting rings, abradable ring sectors, elastic centering elements, and a shroud supporting ring sectors inserted radially to the supporting shroud, between the elastic elements and the abradable ring sectors, which are attached to said supporting shroud, which has a volume varying according to temperature, due to the action of fluid supply elements.