Inter-turbine Casing Sealing Device for Turbofan Cooling

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Solution Overview

Problem

The existing cooling systems for turbofan turbines suffer from leaks through operational clearances in the inter-turbine casing, leading to inefficiencies in cooling air distribution and reduced component lifespan, necessitating increased airflow rates.

Innovation Solution

An inter-turbine casing with a sealing device featuring a base and an elastic peripheral skirt, installed between the outer and intermediate rings, which compresses to prevent cooling air leaks and absorb relative movements, along with sleeves connecting these rings to direct airflow effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If cooling air is fed through the outer ring, fairings and inner rings to cool thermally stressed components, then the components are cooled, but cooling air leaks through operating clearances between divided fairing sectors, causing shortfall in cooling circuit performance

Engineering Contradiction:

Improvecooling of thermally stressed componentsVSAvoidcooling air leaks

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The sealing device extracts and removes the harmful leakage path by inserting a sealing element into the operating clearance between fairing sectors. The sealing device comprises a base with an orifice for cooling air passage and a peripheral skirt that seals against the intermediate ring, effectively taking out the leakage problem from the system while maintaining necessary operational clearances.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The sealing device acts as an intermediary element between the outer ring and intermediate ring. It mediates between the conflicting requirements of maintaining operating clearances for thermal expansion and preventing cooling air leaks. The peripheral skirt of the sealing device seals against the intermediate ring while the base with its orifice allows controlled cooling air passage, thus mediating between sealing and cooling requirements.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If fairings are divided into sectors to allow operating clearance for thermal expansion, then thermal expansion is accommodated, but cooling air escapes through the clearances between sectors, reducing cooling circuit performance

Engineering Contradiction:

Improveaccommodation of thermal expansionVSAvoidcooling air flow rate

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The sealing device applies local quality by differentiating between regions: the peripheral skirt provides sealing in the radial direction to prevent cooling air escape, while the base with its orifice maintains local cooling air passage. This local differentiation allows the system to simultaneously accommodate thermal expansion through sector division while preventing harmful leaks at specific locations.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The peripheral skirt of the sealing device functions as a flexible sealing element that can adapt to relative movements and thermal expansions between fairing sectors. This flexible structure maintains sealing effectiveness while accommodating the necessary operational clearances for thermal expansion, thus preserving both adaptability and cooling air quantity.

Inventive Principle:

Principle #30Flexible shells and thin films

3Temperature

If the flow rate of cooling air is increased to compensate for leaks, then cooling performance is maintained, but the efficiency of the cooling circuit is reduced due to optimized airflow requirement

Engineering Contradiction:

Improvecooling performanceVSAvoidcooling circuit efficiency

Core Design Contradiction:

TemperatureVSProductivity

Solution Approach 1:

The sealing device converts the harmful leakage effect into a beneficial controlled flow path. By providing a defined orifice in the base, it transforms the uncontrolled leakage through fairing sector clearances into a controlled cooling air passage that can be optimized for efficient flow. This converts the harmful leak into a beneficial feature where the sealing device itself becomes part of the controlled cooling circuit.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 minimizes cooling air leaks, ensuring optimal airflow and extending the lifespan of cooled components by maintaining efficient cooling circuit performance.

Implementation Method 1

a peripheral skirt which is able to be compressed and expanded elastically

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8162593B2Inter-turbine casing with cooling circuit, and turbofan comprising it

Publication Date: 2012.04.24 SAFRAN AIRCRAFT ENGINES SAS

AI summary

An inter-turbine casing for a turbofan is disclosed. The casing includes an outer ring, an inner ring, and an intermediate ring between the inner ring and the outer ring. The inner and intermediate rings have respective openings for the passage of cooling air. The casing includes at least one sealing device, arranged between the outer ring and the intermediate ring, with a base, provided with at least one orifice for the passage of cooling air, and a peripheral skirt which is able to be compressed and expanded elastically. The base bears against the outer ring and the peripheral skirt bears against the intermediate ring.