Turbine Fan Case Manifolded Tip Injection Air Recirculation
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Solution Overview
Problem
Integrating air recirculation into fan cases of gas turbine engines poses design challenges due to the complex containment systems, which can compromise the structural integrity and functionality of the fan case.
Innovation Solution
The integration of an air recirculation duct with strategically positioned extraction and injection ports, supported by an annular case and fan track liner, allows for the recirculation of gases while maintaining the structural integrity of the fan case by utilizing specific zones and configurations that avoid high-strain areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If air recirculation passages are integrated into the fan case, then stall margin is enhanced and engine performance is improved, but the structural integrity and containment functionality of the fan case may be compromised
Solution Approach 1:
The fan case is divided into distinct functional zones: a containment zone with solid metallic shroud and liner for structural integrity, and a recirculation zone with extraction/injection ports for air recirculation. The fan track liner is segmented to allow extraction ports at the aft end while maintaining forward containment capability. This segmentation allows the fan case to simultaneously achieve enhanced stall margin through air recirculation and maintain structural integrity through dedicated containment structures.
2Productivity
If air recirculation passages are integrated into the fan case, then stall margin is enhanced, but the device complexity increases due to additional extraction ports, injection ports, and manifolds
Solution Approach 1:
The fan case structure serves multiple functions simultaneously: the metallic shroud and liner provide both structural containment and serve as the framework for air recirculation passages. The extraction ports and injection ports are integrated into the existing fan case geometry rather than being separate components. The manifold system utilizes the available space within the fan case assembly, allowing a single structural component to fulfill both containment and air recirculation functions, thereby reducing overall device complexity.
3Productivity
If extraction ports are positioned at the aft end of the fan track liner, then air recirculation is achieved, but the containment functionality in high-strain areas may be compromised
Solution Approach 1:
Different regions of the fan track liner are assigned different functional qualities: the forward end maintains solid containment structure for high-strain areas to ensure reliability, while the aft end incorporates extraction ports for air recirculation. This local differentiation allows the structure to be optimized for containment where needed and for recirculation where appropriate, resolving the contradiction between air recirculation performance and containment reliability in high-strain zones.
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 configuration effectively enhances stall margin without compromising the containment functionality, allowing for efficient air recirculation that improves engine performance while maintaining the structural integrity of the fan case.
Implementation Method 1
The air recirculation duct may be configured to direct a portion of gases flowing through a gas path of the gas turbine engine from an aft end of the fan track liner into the gas path axially forward of a forward end of the fan track liner
Data Source
AI summary
A fan case assembly adapted for use with a gas turbine engine includes a fan track liner and an annular case. The fan track liner extends circumferentially at least partway about a central axis of the gas turbine engine. The annular case is configured to support the fan track liner at a radial position relative to the central axis. The fan case assembly further includes an air recirculation duct configured to redirect air around the fan track liner.