Turbine Casing Tip Clearance Control via Segmented Impingement
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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 carrier segment with impingement apertures is used to control the temperature of the turbine casing by passing air of a predetermined temperature through these apertures, allowing for precise heating or cooling to match the radial expansion of the blades and casing, thereby maintaining optimal tip clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing temperature control systems are used to control turbine casing temperature, then tip clearance can be maintained under stable conditions, but the system becomes complex and unresponsive during transient power increases
Solution Approach 1:
The carrier is divided into multiple carrier segments that can be independently positioned around the turbine casing. Each segment can be independently adjusted radially to control tip clearance at different locations, allowing localized temperature management without requiring a complex system-wide solution.
Solution Approach 2:
The carrier segments are designed to be radially adjustable rather than fixed, enabling dynamic response to changing thermal conditions. This allows the tip clearance to be actively controlled during transient power increases by moving segments radially inward or outward as needed.
2Reliability
If existing temperature control systems are used, then some tip clearance control is achieved, but the response time during transient power changes is insufficient
Solution Approach 1:
The impingement apertures are pre-positioned in the carrier segments to direct hot gas flow onto the casing surface before the casing needs thermal expansion. This preliminary heating action ensures the casing responds quickly to transient power increases, maintaining tip clearance without requiring complex real-time control systems.
Solution Approach 2:
The system uses pneumatic flow of hot gas through the impingement apertures to rapidly heat the turbine casing. This gas-based thermal transfer mechanism provides faster response compared to conventional thermal control methods, enabling quick adaptation during transient power changes.
3Reliability
If complex temperature control systems are implemented, then tip clearance control improves, but manufacturing cost and system weight increase
Solution Approach 1:
The carrier segments serve multiple functions: they support the turbine blades, control tip clearance through radial adjustment, and direct hot gas flow onto the casing through impingement apertures. This multi-functionality eliminates the need for separate temperature control components, reducing overall system weight and complexity.
Solution Approach 2:
The carrier segments utilize the existing hot gas flow from the turbine to heat the casing, rather than requiring external heating systems. The impingement apertures simply redirect already-present hot gas, making the system self-sufficient and avoiding additional weight from external thermal control equipment.
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 solution provides a simpler, more efficient method to control turbine blade tip clearance, enhancing engine efficiency and responsiveness during transient power changes without adding weight or complexity, while maintaining optimal tip clearance and reducing the risk of rubbing or re-rubbing.
Implementation Method 1
passing air of a predetermined temperature through these apertures, allowing for precise heating or cooling to match the radial expansion of the blades and casing
Implementation Method 2
the radial expansion of the casing can be more accurately matched in a responsive manner to that of the turbine disc/blades
Data Source
AI summary
An arrangement for a gas turbine engine that includes a turbine blade configured to rotate about an axis, a casing radially outside of the turbine blade, and a carrier segment mounted to the casing so as to define a first impingement space therebetween. The carrier segment is positioned radially outside the turbine blade and includes a first impingement carrier wall, a main carrier wall, and a cooling chamber. The first impingement carrier wall is adjacent to and radially inside of the first impingement space, and the first impingement carrier wall includes a first aperture. The main carrier wall is radially inside of the first impingement carrier wall. The cooling chamber is radially inside of the main carrier wall. Additionally, an intermediate chamber is disposed radially between the cooling chamber and the first impingement space. A second aperture is configured to allow ingress of air into the intermediate chamber.