Gas Turbine Casing Perforations for Uniform Thermal Deformation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing methods for reducing clearance between the tips of rotary blades and a stationary ring assembly in a gas turbine are insufficient due to non-uniform thermal deformation of the support ring, leading to uneven temperature fields and mechanical stress.

Innovation Solution

A turbine casing with a circumferential wall and perforations that allow uniform air ventilation to the outside face, providing rotary motion and reducing temperature gradients, thereby ensuring uniform deformation of the support ring.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the diameter of the stationary ring assembly is varied to reduce blade tip clearance, then the clearance is reduced, but non-uniform thermal deformation of the support ring occurs causing uneven temperature fields and mechanical stress

Engineering Contradiction:

Improveblade tip clearanceVSAvoidtemperature uniformity

Core Design Contradiction:

Manufacturing precisionVSTemperature

Solution Approach 1:

The invention applies local quality by introducing ventilation holes at specific locations on the support ring to create localized cooling zones. These holes are strategically positioned to address the non-uniform temperature distribution, delivering cooling air precisely where thermal deformation occurs, thereby achieving uniform temperature field without compromising blade tip clearance control.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention changes the thermal parameter (temperature distribution) of the support ring by introducing controlled air flow through ventilation holes. This parameter change transforms the non-uniform temperature field into a uniform one, preventing thermal deformation while maintaining the ability to control blade tip clearance through ring assembly diameter adjustment.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the diameter of the stationary ring assembly is varied to reduce blade tip clearance, then the clearance is reduced, but mechanical stress on the support ring increases

Engineering Contradiction:

Improveblade tip clearanceVSAvoidmechanical stress

Core Design Contradiction:

Manufacturing precisionVSStress or pressure

Solution Approach 1:

The invention changes the thermal parameter (temperature distribution) of the support ring to prevent thermal deformation. By uniforming the temperature field through ventilation, the mechanical stress caused by differential thermal expansion is reduced, allowing the support ring to maintain structural integrity even when the ring assembly diameter is adjusted for optimal blade tip clearance.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If ventilation holes are added to the support ring to uniform temperature distribution, then temperature uniformity is improved, but device complexity increases

Engineering Contradiction:

Improvetemperature uniformityVSAvoidsupport ring structure

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The invention applies the porous materials principle by incorporating ventilation holes into the support ring structure. These holes create a porous-like flow path that allows cooling air to pass through the support ring, achieving uniform temperature distribution. The implementation uses simple circular holes arranged in a pattern, avoiding complex geometries while effectively addressing thermal deformation.

Inventive Principle:

Principle #31Porous materials

Solution Approach 2:

The invention uses pneumatic principles by introducing compressed air or cooling air flow through the ventilation holes in the support ring. This pneumatic cooling system creates convection currents that uniformly distribute heat across the support ring, achieving temperature uniformity without requiring complex mechanical or thermal control systems.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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

This solution maintains optimal blade clearance, enhances engine performance, and increases the ring support's lifetime by reducing mechanical stresses and temperature gradients, while being cost-effective.

Implementation Method 1

a plurality of perforations (12) enabling air to be delivered for ventilating the outside face (22e) of the circumferential wall (22) in uniform manner

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

the axis of each hole is inclined relative to the axis of the turbine at an angle serving advantageously to impart to the air the rotary motion that is necessary and sufficient for ensuring the looked-for temperature uniformity

Methodology Applied

Scientific EffectRotary motion:

Implementation Method 3

the turbine casing of the invention thus enables the temperature field of the support ring to be made uniform, so that the support deforms in uniform manner around its entire circumference

Methodology Applied

Scientific EffectThermal convection: Convection

Implementation Method 4

the temperature gradients are smaller and the mechanical stresses are thus reduced

Methodology Applied

Scientific EffectTemperature gradient reduction: Temperature Gradient

Data Source

PatentUS7641442B2Device for controlling clearance in a gas turbine

Publication Date: 2010.01.05 SAFRAN AIRCRAFT ENGINES SAS

AI summary

The turbine casing includes a circumferential wall coaxially surrounding a ring that surrounds the moving blades of the turbine. The casing includes a plurality of perforations delivering air for ventilating the outside face of the circumferential wall in uniform manner.