Rotatable Nozzle Aircraft Exhaust Alignment
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Solution Overview
Problem
Conventional aircraft exhaust systems face issues due to non-concentric alignment of primary and secondary exhaust ducts caused by engine movement relative to the airframe, leading to turbulent gas flow and overheating of components, which affects performance and increases temperatures.
Innovation Solution
An exhaust system with a slip joint and drag link maintains concentric alignment between ducts and includes a rotatable nozzle to direct exhaust flow optimally, using a high-temperature o-ring seal and self-lubricated bearing coating, supported by struts with uni-ball connectors for axial movement, and an actuator system for controlled rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the primary exhaust duct is attached directly to the engine and moves with the engine, then the exhaust system adapts to engine movement, but the primary duct becomes non-concentric with the secondary duct, causing turbulent flow and overheating
Solution Approach 1:
The exhaust system employs a rotatable nozzle assembly that can dynamically adjust its orientation to maintain concentric alignment between the primary and secondary exhaust ducts despite engine movement. The nozzle rotates about the exhaust flow axis to compensate for misalignment, ensuring continuous optimal exhaust flow and preventing turbulent conditions.
2Adaptability or versatility
If the exhaust ducts become non-concentric due to engine movement, then engine position flexibility is maintained, but exhaust gas flow becomes directionally biased, resulting in poor ejector performance and overheating
Solution Approach 1:
The rotatable nozzle assembly dynamically adjusts its orientation to maintain proper exhaust flow alignment, preventing directionally biased flow and turbulent conditions that would cause overheating. The nozzle rotation ensures consistent concentric alignment between ducts regardless of engine position changes.
Solution Approach 2:
The system changes the orientation parameter of the nozzle assembly to maintain optimal exhaust flow conditions. By rotating the nozzle about the exhaust axis, the system adjusts the flow direction to compensate for engine movement and prevent overheating of surrounding components.
3Device complexity
If a fixed nozzle configuration is used, then the exhaust system structure is simple, but the exhaust flow direction cannot be optimized, leading to poor ejector performance and increased temperatures
Solution Approach 1:
The nozzle assembly is designed to rotate about the exhaust flow axis, transforming from a fixed to a dynamic configuration. This rotation capability allows the system to optimize exhaust flow direction for maximum ejector performance while maintaining relatively simple structural implementation through the rotation mechanism.
Data Source
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AI summary
An exhaust system for an aircraft has a primary exhaust duct for communicating exhaust gas from an engine exhaust exit and is configured for movement with the engine. A secondary exhaust duct is in fluid communication with the primary exhaust duct and is movably mounted to the airframe. The secondary duct has a portion selectively rotatable relative to the remainder of the secondary duct for directing the exhaust gas vector. The system has means for maintaining a generally consistent relative alignment between the primary duct and the secondary duct.