Segmented Variable Area Nozzle for Turbofan Engine Control
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Solution Overview
Problem
Existing variable area nozzle systems for turbofan aircraft engines are heavy, expensive, and complex, making them inefficient for cost-effective control of engine output under varying flight conditions.
Innovation Solution
A translating variable area nozzle assembly with two or more nozzle segments and a split beavertail fairing, allowing for selective movement between stowed and deployed positions to adjust the fan nozzle exit area and bypass flow, utilizing a guide mechanism and actuators for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If prior variable area nozzle systems are used to control engine output under varying flight conditions, then engine performance can be adjusted, but the systems are heavy, expensive, and complex in structure and operation
Solution Approach 1:
The nozzle is divided into multiple segments (typically three) that can move independently relative to each other. Each segment has its own actuator, allowing simplified control of complex area changes. The segments are connected by hinges that enable rotation to adjust the effective nozzle exit area without requiring complex coordinated movement of multiple components
Solution Approach 2:
The nozzle area is made dynamically adjustable during engine operation through rotation of the segmented structure. The segments can be rotated about hinge axes to change the effective exit area, allowing the nozzle to adapt to varying flight conditions. This dynamic adjustment replaces complex fixed-geometry systems with multiple moving parts
2Adaptability or versatility
If prior variable area nozzle systems are used to control engine output, then bypass flow characteristics can be adjusted, but the systems require coordinated movement of multiple components with complex drive mechanisms
Solution Approach 1:
The nozzle is segmented into independent sections that can be controlled separately. Each segment has its own actuator and hinge mechanism, allowing bypass flow control to be achieved through simple rotation of individual segments rather than coordinated movement of multiple components. This segmentation simplifies the drive mechanism while maintaining flow control capability
Solution Approach 2:
The nozzle employs dynamic rotation of segments about hinge axes to control bypass flow characteristics. This rotational movement is simpler to implement and control than the coordinated linear or angular movement required by prior systems. The dynamic adjustment allows real-time bypass flow optimization with reduced operational complexity
3Productivity
If the fan nozzle exit area is varied to optimize engine performance, then bypass flow characteristics improve, but noise and turbulence may increase
Solution Approach 1:
The segmented nozzle structure allows different local flow characteristics to be created at different sections of the nozzle exit. By independently adjusting segment positions, the flow distribution across the exit area can be optimized to maintain efficiency while reducing localized turbulence and noise generation. The leading edge geometry of each segment can be tailored to promote smooth flow transitions
Data Source
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AI summary
A nacelle assembly (12) includes a first portion having an outer fairing and a trailing edge, and a translatable variable area fan nozzle (50). The fan nozzle (50) includes two or more nozzle segments (54, 56), each nozzle segment having first and second opposed ends and a leading edge. The nozzle segments (54, 56) are selectively movable between a stowed position and one or more deployed positions. In the deployed position, an upstream bypass flow exit (60) is formed between the trailing edge and the leading edge. The nacelle assembly (12) further includes a guide mechanism (104) for guiding the nozzle segments (54, 56) between the stowed position and the deployed position. A split beavertail fairing shields the guide mechanism against air flow when the nozzle segments are in the stowed position.