Compressor Clearance Control Using Insulated Bleed-Air Routing
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Solution Overview
Problem
Existing methods to reduce clearance between blade tips and outer air seals in gas turbine engines lead to heat up of exhausted air, negatively impacting performance of other engine components.
Innovation Solution
A clearance control system that redirects a portion of bleed air from the high pressure compressor to cool the inner case structure using insulated pipes, preventing heat transfer from higher-temperature bleed air and maintaining efficient cooling for other engine components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bleed air is used to cool the inner case structure to reduce clearance, then compressor efficiency is improved, but the exhausted air becomes overheated which negatively impacts other engine components
Solution Approach 1:
The system segments the bleed air flow into two separate paths: one path directs cooler upstream bleed air to cool the inner case structure and reduce clearance, while the other path allows hotter downstream bleed air to continue to turbine cooling functions. This segmentation prevents the mixed overheated air from reaching the turbine, resolving the contradiction between compressor efficiency improvement and turbine temperature requirements.
Solution Approach 2:
A valve system acts as an intermediary to control and direct different portions of bleed air to different destinations. The valve selectively routes upstream cooler bleed air to the inner case cooling function while preventing this cooled air from mixing with and overheating the air destined for turbine cooling, thus maintaining appropriate temperatures for both functions.
2Manufacturing precision
If cooler upstream bleed air is directed to cool the inner case structure, then outer air seal diameter contracts and clearance reduces, but the air must be carefully managed to prevent overheating
Solution Approach 1:
The system applies local quality by directing cooler upstream bleed air specifically to the inner case structure where cooling is needed for clearance control, while allowing hotter downstream bleed air to proceed to turbine cooling functions. This localized application of different temperature air to different locations achieves precise clearance control without compromising overall temperature management.
Solution Approach 2:
The valve system dynamically adjusts the routing of bleed air based on operating conditions, selectively directing cooler upstream air to inner case cooling when clearance reduction is needed, while maintaining the ability to redirect flow as conditions change, providing adaptive control of both clearance and temperature.
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
Improves high pressure compressor efficiency by minimizing clearance and maintaining effective cooling without overheating the redirected bleed air, enhancing overall engine performance.
Implementation Method 1
an insulated pipe fluidly coupled to the control valve; wherein the control valve redirects a portion of the source of bleed air towards an inner case structure of the high pressure compressor and thereafter to the insulated pipe
Implementation Method 2
utilize a portion of upstream, cooler compressor bleed flow to cool the rear inner case structure that houses the outer air seals
Implementation Method 3
The cooling effect then contracts the outer air seal diameter and reduces the clearance to the blade tips
Data Source
AI summary
A high pressure compressor for a gas turbine engine. The high pressure compressor including: a clearance control system, the clearance control system including: a control valve fluidly coupled to a source of bleed air of the high pressure compressor, the control valve configured for movement between a first position and a second position; an insulated pipe fluidly coupled to the control valve; and wherein the control valve redirects a portion of the source of bleed air towards an inner case structure of the high pressure compressor and thereafter to the insulated pipe when it is in the first position and wherein the source of bleed air is not redirected towards the inner case structure of the high pressure compressor and the insulated pipe when the control valve is in the second position.