Asymmetric Fixed Geometry Fan Nozzle for Thrust Vectoring
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Solution Overview
Problem
Traditional fixed geometry approaches to thrust optimization in turbofan engines compromise between minimizing exhaust jet interaction noise and wing flap dynamic loading, leading to non-optimum performance in fuel flow and noise reduction, especially in close coupled engine installations.
Innovation Solution
A fixed geometry fan nozzle with asymmetric convergence/divergence and curvature is introduced, creating a pressure differential to vector the exhaust plume differently based on operating conditions, achieving unchoked and choked flow states, which reduces noise and improves thrust efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional symmetric fixed geometry nozzle is used, then the structure is simple and manufacturing is easy, but thrust optimization is compromised and exhaust jet interaction noise is not minimized
Solution Approach 1:
The patent applies asymmetry by providing a nozzle with asymmetric convergence/divergence and wall curvature varying angularly from a midplane. The first wall portion has different convergence/divergence and curvature characteristics than the second wall portion, enabling differential flow vectoring. This asymmetric geometry creates pressure differentials that vector the exhaust plume to reduce jet flap noise and shock cell noise while maintaining thrust efficiency, resolving the contradiction between manufacturing simplicity and performance optimization.
Solution Approach 2:
The patent implements local quality by varying the convergence/divergence and wall curvature specifically in certain angular regions from the midplane. The asymmetric characteristics are localized to specific portions of the nozzle rather than applying uniform changes throughout, allowing targeted flow control where needed while maintaining simpler geometry in other regions, thus balancing manufacturing ease with performance improvement.
2Productivity
If a variable geometry nozzle system is used, then thrust optimization and noise reduction are improved, but device complexity and cost increase
Solution Approach 1:
The patent applies self-service by designing a fixed geometry nozzle that automatically adapts its flow characteristics based on operating conditions. The asymmetric convergence/divergence and wall curvature create pressure differentials that naturally vector the exhaust plume without requiring external control systems, actuators, or variable geometry mechanisms. The nozzle structure itself performs the flow control function, eliminating the need for complex variable geometry systems while maintaining thrust optimization and noise reduction benefits.
3Adaptability or versatility
If asymmetric convergence/divergence is introduced, then flow vectoring capability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the nozzle into distinct functional regions: a midplane reference, first wall portions with specific asymmetric characteristics, and second wall portions with different characteristics. This segmentation allows each region to be designed and manufactured with focused precision requirements, making the overall asymmetric geometry more manufacturable while maintaining the flow vectoring capability.
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 solution enables simultaneous optimization of aircraft performance, reduced wing component loads, and lower noise levels by differentially vectoring the exhaust plume, reducing jet flap noise and shock cell noise, while avoiding the complexity and cost of variable geometry systems.
Implementation Method 1
creating a pressure differential to vector the exhaust plume differently based on operating conditions
Implementation Method 2
induce flow turning and axially symmetrically equal pressure
Implementation Method 3
creating a sonic wave for choked flow through the throat of the nozzle
Implementation Method 4
a nozzle pressure ratio above the threshold creating a sonic wave for choked flow through the throat of the nozzle
Implementation Method 5
reducing jet flap noise and shock cell noise
Implementation Method 6
The exhaust nozzle includes spaced apart fan nozzle inner and outer walls which form an annular exhaust gas flow path therebetween
Data Source
Figure 1A
Figure 1B~1C
Figure 2
AI summary
A flow vectoring turbofan engine employs a fixed geometry fan sleeve and core cowl forming a nozzle incorporating an asymmetric convergent/divergent (con-di) and / or curvature section which varies angularly from a midplane for reduced pressure in a first operating condition to induce flow turning and axially symmetric equal pressure in a second operating condition for substantially axial flow.