Fan Case Tip Injection Air Recirculation Passage
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Solution Overview
Problem
Integrating air recirculation systems into fan cases of gas turbine engines poses design challenges due to the need to maintain structural integrity for fan blade containment, particularly in incorporating extraction and injection ports without compromising the containment function.
Innovation Solution
The fan case assembly includes an annular case with strategically positioned extraction and injection ports, supported by a conduit system that directs gases from the aft end of the fan track liner forward, integrated through specific zones of the fan case to maintain structural integrity while allowing for air recirculation, and a valve to control gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If extraction and injection ports are incorporated into the fan case to enable air recirculation, then stall margin is improved, but structural integrity for fan blade containment is compromised
Solution Approach 1:
The fan case is divided into multiple functional zones: a containment zone with thick walls for blade containment, and recirculation zones with integrated extraction and injection ports. This segmentation allows different parts of the fan case to serve different functions - structural containment versus air recirculation - resolving the contradiction between maintaining structural integrity and enabling stall margin improvement through port integration
Solution Approach 2:
Different wall thicknesses and material properties are applied to different regions of the fan case. The containment zone maintains thick walls for structural integrity, while the recirculation zones incorporate ports with localized structural reinforcements. This local quality variation allows the fan case to simultaneously provide blade containment and enable air recirculation for improved stall margin
2Productivity
If air recirculation system is integrated into the fan case, then gas flow management is enhanced, but device complexity increases
Solution Approach 1:
The air recirculation system is merged with the fan case structure itself. The extraction ports, injection ports, and associated conduits are integrated into the fan case walls, combining the containment function and recirculation function into a single unified structure. This eliminates the need for separate external recirculation systems, reducing overall device complexity while maintaining gas flow management efficiency
Solution Approach 2:
The fan case is designed with multi-functionality: it simultaneously serves as the containment structure for blade-off events and as the housing for the air recirculation system. The same structural component (fan case) performs both protective and flow-management functions, reducing the number of separate components needed and simplifying the overall system
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 by allowing air recirculation without compromising the structural integrity of the fan case, enabling efficient gas flow management and containment functionality.
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.