Integrated Ram-Air Intake for Gas Turbine Tip Clearance Control

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Solution Overview

Problem

Existing gas turbine engines face a conflict between minimizing rotor tip clearance for maximum thermodynamic efficiency and avoiding tip rubs, which leads to increased weight, complexity, and cost due to extensive ducting required for Tip Clearance Control (TCC) systems, and resonance-related noise issues.

Innovation Solution

An air intake system with a ram-air intake that houses a heat exchanger and integrates TCC ducts, reducing the need for separate air off-takes and minimizing ducting length, thereby reducing weight, complexity, and space usage within the engine core.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If extensive ducting is used to guide air from the front of the bypass duct to the turbine casings, then the TCC system can be positioned at the front to avoid high temperatures, but this adds weight, complexity, and cost to the gas turbine engine

Engineering Contradiction:

ImproveTCC system reliabilityVSAvoidducting complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the TCC system with the heat exchanger by positioning both components at the rear of the engine and integrating their air intake requirements. This merging eliminates the need for separate extensive ducting systems, reducing overall system complexity while maintaining functional reliability of both the TCC and heat exchanger systems.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

Instead of positioning the TCC system at the front of the engine to avoid high temperatures (conventional approach), the patent inverts this approach by locating the TCC system at the rear near the heat exchanger. This inversion allows both systems to share common ducting and air supply pathways, reducing overall system complexity despite the temperature exposure.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If extensive ducting is used to guide air from the front of the bypass duct to the turbine casings, then the TCC system can be positioned at the front to avoid high engine temperatures, but this takes up valuable space in the engine core

Engineering Contradiction:

ImproveTCC system reliabilityVSAvoidengine core space

Core Design Contradiction:

ReliabilityVSVolume of stationary object

Solution Approach 1:

The patent merges the TCC system and heat exchanger air supply pathways, allowing both systems to utilize the same ducting infrastructure. This consolidation significantly reduces the volume of ducting required in the engine core compared to having separate ducting systems for each component.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

By inverting the conventional front-mounted TCC arrangement and positioning it at the rear near the heat exchanger, the patent enables both systems to share common air supply pathways, thereby reducing the space occupied by ducting in the engine core.

Inventive Principle:

Principle #13The other way round (Inversion)

3Reliability

Engineering Contradiction:

ImproveTCC system reliabilityVSAvoidresonance and noise

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent combines the TCC and heat exchanger systems into a single integrated arrangement at the rear of the engine. This merging drastically shortens the air supply ducts, eliminating the resonance and noise issues that arise from extended ducting while preserving the TCC system's ability to function reliably.

Inventive Principle:

Principle #5Merging (Combining)

4Loss of energy

If rotor tip clearance is minimized for maximum thermodynamic efficiency, then engine efficiency is maximized, but this increases the risk of tip rubs between rotor blades and casing

Engineering Contradiction:

Improvethermodynamic efficiencyVSAvoidservice life

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent utilizes thermal expansion and contraction of the turbine casing as a control mechanism. By regulating cooling airflow to the casing, the system dynamically adjusts the casing's thermal state, causing controlled expansion and contraction that maintains optimal tip clearance while preventing tip rubs, thus resolving the conflict between efficiency and service life.

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

This integrated air intake system enhances thermodynamic efficiency by minimizing rotor tip clearance while reducing the risk of tip rubs and noise, resulting in a more efficient and cost-effective gas turbine engine design.

Implementation Method 1

the body portion of the ram-air intake houses a heat exchanger

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

The term 'ram-air intake' is intended to refer to an air intake which uses the dynamic air pressure to increase the static air pressure inside of the body portion

Methodology Applied

Scientific EffectDynamic pressure conversion: Bernoulli Effect

Implementation Method 3

The TCC system includes a valve which is actuable to control cooling airflow to an exterior of the casing to control expansion and contraction of the casing to thereby control tip clearance

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3572660B1Air intake system

Publication Date: 2022.06.29 ROLLS ROYCE PLC

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AI summary

There is provided an air intake system for providing air to a tip clearance control system. The air intake system comprises a ram-air intake having a scoop portion and a body portion. The body portion of the ram-air intake houses a heat exchanger.