Expanding Shell Bypass Flow Control Device
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Solution Overview
Problem
Current gas turbine engines face challenges in optimizing the bypass flow control to enhance aerodynamic efficiency and operability, particularly in managing the bypass air stream effectively across various engine cycles.
Innovation Solution
An expanding shell bypass flow control device with sliding metallic segments that alter the annular area of the bypass flowpath, accompanied by a seal upstream to manage the flow control device's position and functionality, allowing for adjustable bypass flow control by changing the overlap of segments to modify the bypass flowpath radius.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed structure including ducted passages is used for bypass flow control, then the device complexity is reduced, but the aerodynamic efficiency and adaptability across various engine cycles deteriorate
Solution Approach 1:
The flow control device is divided into multiple arcuate segments that can independently pivot relative to each other. This segmentation allows the device to achieve complex flow control patterns through coordinated movement of individual segments, providing adaptability across different engine cycles while maintaining a relatively simple overall structure based on modular components.
Solution Approach 2:
The flow control device transitions from a fixed structure to a dynamic structure where arcuate segments can pivot about stationary pins. This dynamic capability enables the device to adjust the bypass flowpath geometry in real-time, optimizing aerodynamic efficiency for different engine operating conditions while the pivoting mechanism remains mechanically simple.
2Ease of operation
If the bypass flow control device structure is simplified, then the ease of manufacture is improved, but the ability to dynamically adjust bypass flow for different engine stages deteriorates
Solution Approach 1:
The device uses multiple identical arcuate segments that can be manufactured using the same processes and then assembled together. This segmentation into standardized components improves ease of manufacture while the ability to pivot these segments provides dynamic flow adjustment capability for different engine operating stages.
Solution Approach 2:
Multiple arcuate segments are combined to form the complete flow control device, with each segment contributing to the overall bypass flowpath. This merging of simple, manufacturable segments creates a complex functional device capable of dynamic adjustment without requiring complex manufacturing processes for individual components.
3Productivity
If the bypass flowpath radius is increased to improve thrust, then the aerodynamic efficiency is improved, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The flow control device dynamically adjusts the bypass flowpath radius by pivoting arcuate segments to different angular positions. This dynamic adjustment allows optimization of thrust generation for different operating conditions without requiring multiple fixed structures or complex control mechanisms, as the same device adapts its geometry through simple pivoting motions.
Data Source
Figure 1a~1b
Figure 2a~3a
Figure 2b~3b
AI summary
A gas turbine engine includes a bypass flowpath between an outer engine case structure and a core engine. The bypass flow exits the engine through a nozzle. A flow control device that can expand or contract is arranged around the nozzle to control the bypass flow and includes a plurality of overlapping arcuate segments. A method of controlling a bypass flow includes providing a flow control device with overlapping segments that defines a bypass flow path, and actuating the segments to change the amount of overlap between segments and therefore the size of the bypass flow path.