Linear Actuator Chevron Nozzle for Jet Engine Noise
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Solution Overview
Problem
Conventional variable area fan nozzles (VAFNs) in jet engines face challenges in optimizing geometry for reduced noise, improved thrust, and fuel efficiency, as they cause drag and are often heavy or expensive due to the use of hydraulically-actuated chevrons or shape memory alloy chevrons.
Innovation Solution
The implementation of a chevron installation system that uses linear actuators to translate chevrons forward and aft within the jet engine cowl, altering the fan nozzle exit area to optimize acoustic performance and fan duct pressures, while minimizing aerodynamic impact and incorporating position sensing features for precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If chevrons are fixed in place to reduce jet engine noise, then acoustic attenuation is improved, but drag increases and thrust is lost
Solution Approach 1:
The chevron elements are made movable rather than fixed, allowing them to dynamically adjust their position between retracted and extended configurations. This enables the system to optimize between noise reduction (when extended) and thrust preservation (when retracted), resolving the contradiction between acoustic attenuation and thrust loss.
Solution Approach 2:
The chevron position is changed as a variable parameter, transitioning between different spatial configurations. By adjusting the chevron extension parameter, the system can optimize performance for different operating conditions, reducing noise when needed while minimizing drag during thrust-critical phases.
2Object-affected harmful factors
If hydraulically-actuated chevrons are used to alter fan nozzle exit area, then noise reduction is improved, but device weight and maintenance cost increase
Solution Approach 1:
The hydraulic actuation system is replaced with a mechanical actuation system using actuators that directly drive the chevron elements. This substitution eliminates the need for hydraulic fluid, pumps, and associated infrastructure, significantly reducing weight and maintenance requirements while maintaining the ability to adjust chevron position for noise reduction.
Solution Approach 2:
The hydraulic system components (fluid, pumps, reservoirs) are extracted from the chevron actuation mechanism. By removing these heavy and maintenance-intensive elements, the invention achieves noise reduction capability with a lighter, simpler actuation system.
3Object-affected harmful factors
If shape memory alloy chevrons are used to reduce noise, then acoustic attenuation is improved, but manufacturing cost increases due to expensive alloys
Solution Approach 1:
The invention replaces expensive shape memory alloy materials with more economical mechanical actuation systems using conventional actuators and structural materials. This substitution maintains the functional capability of noise reduction while dramatically reducing manufacturing costs through the use of standard, readily available materials.
Solution Approach 2:
The material composition parameter is changed from expensive shape memory alloys to conventional structural materials paired with mechanical actuators. This parameter change achieves the same functional outcome (noise reduction through chevron adjustment) while improving ease of manufacture and reducing cost.
4Loss of energy
If chevrons are made movable to reduce drag, then thrust efficiency is improved, but device complexity increases
Solution Approach 1:
The chevron system is segmented into individual movable elements, each capable of independent or coordinated actuation. This segmentation allows for simplified control of each element while achieving complex overall performance optimization, balancing thrust efficiency improvement with manageable system complexity.
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 enhances acoustic attenuation, thrust efficiency, and fuel efficiency by allowing precise adjustment of the fan nozzle exit area, reducing noise and improving engine performance across various flight conditions without inducing high torsional loads or mechanical issues.
Implementation Method 1
a first linear actuator coupled to the first chevron and configured to translate the first chevron forward or aft
Implementation Method 2
altering a gas flow path of an airfoil
Data Source
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AI summary
A trans cowl for a jet engine includes a chevron coupled with a linear actuators. The chevron is movable by the linear actuator forward or aft to change a gas flow path formed by an core cowl and thrust reverser translating cowl. In a first position, the chevrons are disposed substantially parallel the gas flow path to attenuate drag and/or loss of engine thrust. In a second position, the chevrons are moved aft to project, or further project, into the gas flow path. In one embodiment, the linear actuator comprises a first component that is coupled with the outer cowl. A second component of the linear actuator is coupled with the chevron. When installed, the linear actuator can be coupled with a controller and an electrical power source. A position sensor coupled with the controller senses a position of the linear actuator and/or the chevron.