Tip Clearance Control Using Cabin Blower Compressor

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Solution Overview

Problem

Conventional tip clearance control systems in gas turbine engines face challenges due to limited pressure ratio for casing cooling, leading to design constraints and increased weight from larger conduits and valves to minimize pressure drop.

Innovation Solution

Integration of a cabin blower system that compresses air for both cabin pressurization and tip clearance control, using a toroidal continuously variable transmission to control flow volume and pressure, allowing shared fluid delivery passages and reducing weight by eliminating separate flow control mechanisms.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If cooling air is bled from the bypass duct in conventional tip clearance control systems, then the system can provide cooling air to the casing, but the pressure ratio available is marginal and larger cross-section conduits and valves are required to minimize pressure drop, which adds weight

Engineering Contradiction:

Improvepressure ratio available for coolingVSAvoidweight of conduits and valves

Core Design Contradiction:

Stress or pressureVSWeight of stationary object

Solution Approach 1:

The patent combines the cabin blower system and tip clearance control system into a single integrated system. The cabin blower compressor serves dual purposes: pressurizing cabin air and providing high-pressure cooling air to the engine casing. This merging eliminates the need for separate bypass duct bleeding systems and their associated large-diameter conduits and valves, thereby reducing weight while maintaining adequate cooling pressure.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The cabin blower compressor is designed to perform multiple functions: it pressurizes air for cabin environmental control and simultaneously provides high-pressure cooling air for tip clearance control. This multi-functionality allows the system to leverage the high pressure generated for cabin pressurization (which would otherwise be wasted) to drive the casing cooling system, eliminating the need for dedicated cooling air extraction systems and their heavy infrastructure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Quantity of substance

If larger cross-section conduits and valves are used to minimize pressure drop, then adequate air delivery volume to the casing can be maintained, but the system weight increases

Engineering Contradiction:

Improveair delivery volume to casingVSAvoidweight of conduits and valves

Core Design Contradiction:

Quantity of substanceVSWeight of stationary object

Solution Approach 1:

The invention changes the pressure parameter of the cooling air by using the high-pressure output from the cabin blower compressor (designed for cabin pressurization requirements) instead of low-pressure air from bypass duct bleeding. This parameter change allows the use of smaller-diameter conduits and valves while maintaining adequate mass flow rate for cooling, because the higher pressure compensates for the reduced cross-sectional area.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If separate flow control mechanisms are provided for cabin blower and tip clearance control, then each function can be controlled independently, but the device complexity and weight increase

Engineering Contradiction:

Improveindependent flow control capabilityVSAvoidnumber of control mechanisms

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The flow control mechanism designed for regulating air flow to the cabin environmental control system is also used to control air flow to the engine casing for tip clearance control. This universal control approach allows independent regulation of both functions through a single system, reducing the number of control components while maintaining the ability to independently adjust flow rates to each destination based on operational requirements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enhances tip clearance control by increasing available pressure for cooling, reducing the size and weight of fluid delivery passages, and maintaining cabin air flow and pressure within acceptable limits regardless of engine operating conditions.

Implementation Method 1

a cabin blower system having a cabin blower compressor; wherein the output of the cabin blower compressor is coupled to and arranged to deliver fluid to the fluid delivery passage

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 2

the cooling air is bled from the bypass duct and delivered to the casing... The air is used to selectively control the thermal growth of the casing, thereby controlling the clearance between blade tips and the casing

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 3

The air is used to selectively control the thermal growth of the casing, thereby controlling the clearance between blade tips and the casing

Methodology Applied

Scientific EffectThermal contraction: Thermal Contraction

Data Source

PatentUS10605107B2Tip clearance control system

Publication Date: 2020.03.31 ROLLS ROYCE PLC

AI summary

A gas turbine engine is disclosed having a tip clearance control system. The tip clearance control system has a cabin blower system, a casing arranged in use about a rotor of a gas turbine engine and a fluid delivery passage. The cabin blower system having a cabin blower compressor arranged in use to compress fluid used in a cabin of an aircraft and to compress fluid conducted via the fluid delivery passage into heat exchange with the casing.