Segmented Impingement Casing for Turbine Tip Clearance Control
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Solution Overview
Problem
Existing systems for controlling the temperature of the turbine casing in gas turbine engines are complex, costly, and inefficient, particularly during transient increases in engine power, leading to suboptimal tip clearance and reduced engine efficiency.
Innovation Solution
A method involving carrier segments with impingement apertures that allow controlled airflow of a predetermined temperature to impinge on the turbine casing, with optional exhaust to optimize temperature control and reduce tip clearance, using a constructionally simpler and more efficient arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a discrete thin impingement plate with through-holes is used to heat the turbine casing quickly, then the responsiveness of temperature control is improved, but the structural complexity and manufacturing difficulty increase
Solution Approach 1:
The impingement plate is divided into multiple segments that can be independently manufactured and assembled. Each segment contains a portion of the through-holes, allowing parallel manufacturing and reducing overall complexity. The segmented structure also enables modular replacement and maintenance.
Solution Approach 2:
The impingement plate segments are nested within the turbine casing structure, with the plate positioned radially inwardly of the casing. This nesting integrates the heating function into the existing casing architecture rather than adding a separate external system, reducing overall device complexity.
2Productivity
If the turbine casing is heated quickly to maintain optimal tip clearance during transient power increases, then engine efficiency is improved, but the risk of thermal stress and deformation increases
Solution Approach 1:
The impingement plate is positioned to deliver heated air to specific localized regions of the turbine casing where tip clearance control is most critical. This localized heating approach maintains engine efficiency while avoiding uniform thermal stress across the entire casing structure.
Solution Approach 2:
The impingement heating system operates periodically or transiently during power increases rather than continuously. The system activates when needed to maintain optimal tip clearance and then reduces or stops heating, allowing the casing to stabilize thermally and reducing cumulative thermal stress.
3Temperature
If the impingement plate is positioned closer to the turbine blades to improve heating efficiency, then temperature control effectiveness is improved, but the risk of blade-rubbing increases
Solution Approach 1:
The impingement plate serves as an intermediary structure positioned between the turbine blades and the outer casing. It delivers heated air to the casing through controlled through-holes while maintaining a safe radial distance from the blade tips, thus mediating between the need for effective heating and the need to prevent blade-rubbing.
Solution Approach 2:
The system replaces direct mechanical contact heating methods with thermal convection through the impingement plate. Hot air is directed through the plate to heat the casing indirectly, eliminating the need for the heating structure to be in direct contact with or extremely close to the rotating blades.
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 approach enhances the responsiveness of the turbine casing temperature control, maintaining optimal tip clearance and engine efficiency during transient power increases, while reducing complexity and cost.
Implementation Method 1
passage therethrough of air of a predetermined temperature from a feed source into impingement onto the turbine casing
Implementation Method 2
as the casing heats up and expands sufficiently to increase the tip clearance again back to an optimum distance
Data Source
AI summary
An engine includes circumferentially spaced turbine blades radially inward a casing and circumscribed by a carrier section having segments, each having a carrier wall radially inward the casing and radially outward the turbine blades. The wall has one or more portions facing the casing. At least one of the portions has one or more impingement apertures for air passage of a predetermined temperature from a feed source into impingement onto the casing. The segments are radially inward the casing and radially outward the turbine blades, with the portions of their respective walls facing the casing. A method of controlling the gas turbine engine turbine casing temperature includes: passing air of a predetermined temperature from a feed source through the apertures in the one or more portions and into impingement on the casing; and optionally exhausting the air impinged onto the casing from a space between the segment and the casing.