Rotating Drum Fan Tip Control for Gas Turbine Stall Margin
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Solution Overview
Problem
Gas turbine engines face challenges with pressure and swirl distortions, which can lead to engine stall and undesirable aeromechanical behavior, particularly in embedded applications where severe distortions occur due to pressure gradients and swirl.
Innovation Solution
A fan case assembly with a plurality of drums and a control unit that can rotate between closed and open positions to manage fluid communication within the engine, minimizing negative effects of pressure and swirl distortions by allowing or blocking fluid paths in response to preselected operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the fan operates in embedded gas turbine applications, then the engine can be compact and integrated, but severe pressure and swirl distortions occur leading to engine stall
Solution Approach 1:
The patent applies dynamics by making the fan blade tips movable through a rotation mechanism. The blade tips can rotate between a first position (normal operation) and a second position (distortion mitigation). This dynamic adjustment allows the system to adapt to varying operating conditions, particularly embedded applications with severe distortions, thereby maintaining stall margin while preserving compactness.
Solution Approach 2:
The patent changes the geometric parameter of the fan blades by rotating the blade tips to different positions. This parameter change modifies the effective blade shape and airflow characteristics, enabling the fan to tolerate severe pressure and swirl distortions in embedded applications without stalling, thus resolving the contradiction between compactness and reliability.
2Device complexity
If the fan blade tips are made fixed, then the structure is simple and reliable, but the fan cannot tolerate severe pressure and swirl distortions
Solution Approach 1:
The patent introduces dynamic capability to the blade tips through a rotation mechanism that can be actuated based on operating conditions. This allows the blade tips to adjust their position to mitigate distortion effects, significantly improving distortion tolerance while adding only minimal structural complexity compared to fixed blade designs.
3Reliability
If the fan blade tips are made adjustable to mitigate distortions, then stall margin improves, but the device complexity increases
Solution Approach 1:
The patent implements a rotation mechanism for the blade tips that provides dynamic adjustability. This mechanism, while adding some complexity, enables the fan to adapt to severe distortions in embedded applications, significantly improving stall margin and operational reliability under varying conditions.
Data Source
AI summary
A gas turbine engine includes a fan and a fan case assembly. The fan includes a fan rotor configured to rotate about an axis of the gas turbine engine and a plurality of fan blades coupled to the fan rotor for rotation therewith. The fan case assembly extends circumferentially around the plurality of fan blades radially outward of the plurality of the fan blades.