Gas Turbine Rear Cowl Variable Area Nozzle
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Solution Overview
Problem
Existing gas turbine engine designs with variable area exhaust nozzles often increase component count, weight, and complexity, compromising efficiency at off-design operating points and thrust recovery.
Innovation Solution
A gas turbine engine with a rear cowl and a blocker plate, where two panels rotate about an axis parallel to the main rotational axis, altering the exhaust aperture area without significant architectural changes, using a motive system to switch between stowed and deployed configurations, and optionally a maintenance configuration, with a blocker plate to prevent exhaust gas leakage and louvers for thrust enhancement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a rear cowl is made selectively rearwardly translatable to open an annular gap and increase exhaust aperture area, then efficiency at off-design operating points is improved, but thrust recovery is compromised due to the upstream location of the additional aperture
Solution Approach 1:
The patent applies dynamics by making the exhaust aperture area variable through rotation of panels about an axis parallel to the engine rotational axis. The panels can be positioned in different configurations (fully retracted, partially rotated, fully rotated) to dynamically adjust the exhaust area according to operating conditions, allowing optimization of both thrust recovery and off-design efficiency.
Solution Approach 2:
The rear cowl is segmented into multiple panels (typically two or more) that can be independently rotated about hinges. This segmentation allows selective adjustment of the exhaust aperture area by rotating individual panels to different angles, providing fine control over the effective exhaust area while maintaining structural integrity.
2Adaptability or versatility
If existing variable area exhaust nozzle systems are implemented, then exhaust aperture area can be varied, but component count increases significantly
Solution Approach 1:
The panels serve multiple functions: they form the rear cowl structure, provide the variable area exhaust aperture when rotated, and can be integrated with thrust reversal mechanisms. This multi-functionality reduces the need for separate components for each function, thereby reducing overall component count while maintaining adaptability.
Solution Approach 2:
The invention merges the variable area exhaust nozzle function with the existing rear cowl structure by integrating rotating panels into the cowl itself. This consolidation eliminates the need for separate variable area nozzle components, reducing component count while achieving the desired exhaust area variation.
3Adaptability or versatility
If existing variable area exhaust nozzle systems are implemented, then exhaust aperture area can be varied, but weight increases significantly
Solution Approach 1:
The panels are designed as thin-walled structures that provide sufficient structural strength while minimizing weight. The use of thin-film-like panel construction allows for large surface areas with minimal material usage, reducing the weight penalty associated with variable area exhaust systems.
4Adaptability or versatility
If existing variable area exhaust nozzle systems are implemented, then exhaust aperture area can be varied, but size increases significantly
Solution Approach 1:
When the panels are in the retracted position, they nest within or flush with the main engine structure, presenting a streamlined outer contour. When rotated, they extend outward to provide the variable area exhaust aperture. This nesting arrangement minimizes the overall engine size while maintaining the capability for area variation.
Data Source
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AI summary
A gas turbine engine (30) comprising a rear cowl (38) defining an exhaust aperture (40) and a motive system. The rear cowl (38) comprises at least one panel (42) and the motive system is operable to selectively move the panel (42) between deployed and stowed configurations by rotation of the panel (42) about an axis substantially parallel to the main rotational axis of the engine (30). This alters the area of the exhaust aperture (40).