Variable Tandem Fan Outlet Guide Vanes for Airflow Distortion
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Solution Overview
Problem
Gas turbine engine fan assemblies experience operability issues due to variations in intake airflow and pressure fluctuations, leading to inefficiencies and potential damage from distortions and disturbances in airflow.
Innovation Solution
A fan assembly with a variable-pitch outlet guide vane system that adjusts the direction of fan exit air to minimize losses caused by distortions, featuring a first and second plurality of variable-pitch outlet guide vanes that rotate to specific angles in response to operating conditions, with a control system to manage their movement and maintain axial flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single row of fixed-pitch outlet guide vanes is used, then the structure is simple, but it cannot compensate for inlet pressure distortions and swirl across varying operating conditions
Solution Approach 1:
The patent applies the dynamics principle by implementing variable-pitch outlet guide vanes that can change their angle relative to the airflow direction based on operating conditions. The vanes are equipped with actuators that adjust their pitch angle dynamically, allowing the system to adapt to different inlet pressure distortions and swirl conditions across various operating points, thereby resolving the contradiction between adaptability and structural simplicity.
Solution Approach 2:
The patent applies segmentation by dividing the outlet guide vane system into multiple independently controllable vanes arranged in one or more rows. Each vane can be adjusted individually or in groups, allowing differential positioning to compensate for non-uniform inlet distortions. This segmentation enables the system to handle complex multi-dimensional flow distortions while maintaining reasonable structural complexity through modular actuation mechanisms.
2Adaptability or versatility
If variable-pitch outlet guide vanes are implemented, then adaptability to operating conditions improves, but device complexity increases
Solution Approach 1:
The patent applies universality by designing a control system that manages multiple variable-pitch vanes using a unified control architecture. The control system receives inputs from sensors monitoring inlet pressure distortions and swirl, then coordinates the pitch adjustment of multiple vanes to achieve flow straightening. This multi-functional control approach allows a single control system to handle various operating conditions and distortion patterns, reducing overall system complexity despite the presence of multiple adjustable vanes.
Solution Approach 2:
The patent applies merging by combining the control mechanisms for multiple variable-pitch vanes into integrated actuation systems. Adjacent vanes are often connected through common actuation linkages or controlled by grouped actuators, reducing the total number of independent control elements. This merging strategy maintains the adaptability benefits of variable-pitch vanes while minimizing the increase in device complexity through consolidated control architecture.
3Reliability
If multiple rows of variable-pitch vanes are used, then flow distortion compensation improves, but manufacturing and maintenance difficulty increases
Solution Approach 1:
The patent applies segmentation by dividing the outlet guide vane system into multiple rows of vanes that can be manufactured and assembled as separate modular units. Each row functions as an independent module that can be fabricated, tested, and installed separately, then integrated into the complete system. This modular segmentation improves flow straightening effectiveness through multi-row configuration while managing manufacturing and assembly complexity through standardized modular components.
Solution Approach 2:
The patent applies preliminary action by pre-assembling and pre-testing variable-pitch vane rows as complete functional modules before final installation. The actuation mechanisms, linkages, and vane assemblies are configured and validated in advance during module fabrication, allowing for quality control and simplification of on-site assembly. This preliminary preparation reduces manufacturing and assembly difficulty despite the complex multi-row variable-pitch configuration.
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
The system reduces forcing, stall, flutter, and flow separation, improving engine performance and efficiency by compensating for inlet pressure distortions and swirl, thereby enhancing the overall operability and thrust of the gas turbine engine.
Implementation Method 1
The outlet guide vane assembly is configured to adjust a direction of the fan exit air received from the plurality of fan blades
Implementation Method 2
the second variable-pitch outlet guide vane being configured to rotate about a second pitch axis to a second vane-pitch angle in order to redirect the fan exit air flowing in the first direction in a second direction to minimize losses created by distortions in fan inlet air
Implementation Method 3
the first variable-pitch outlet guide vane being configured to rotate about a first pitch axis to a first vane-pitch angle
Implementation Method 4
configured to rotate about a first pitch axis to a first vane-pitch angle in response to the gas turbine engine operating at a given operating condition
Implementation Method 5
a control system configured to rotate the first plurality of variable-pitch outlet guide vanes and to rotate the second plurality of variable-pitch outlet guide vanes
Implementation Method 6
The system reduces forcing, stall, flutter, and flow separation, improving engine performance and efficiency
Implementation Method 7
The system reduces forcing, stall, flutter, and flow separation, improving engine performance and efficiency
Data Source
AI summary
A fan assembly includes a fan duct, an inlet fan, and an outlet guide vane assembly. The inlet fan includes blades adapted to force fan exit air toward an aft end of the fan duct. The outlet guide vane assembly is located in the fan duct downstream of the inlet fan and is configured to adjust a direction of the fan exit air received from the blades. The outlet guide vane assembly includes a first plurality of vanes configured to rotate to redirect the fan exit air in a first direction, and a second plurality of vanes located downstream of the first plurality of vanes. The second plurality of vanes are configured to rotate to redirect the fan exit air flowing in the first direction in a second direction to minimize losses created by distortions in fan inlet air and created by the first vanes.