Adjustable Core Cowl Grooves for Gas Turbine Noise Reduction
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Solution Overview
Problem
High bypass turbofan engines face challenges with increased nacelle size leading to weight, noise, and drag, which negatively impact efficiency during non-cruise flight conditions.
Innovation Solution
A core nacelle with a selectively adjustable core cowl featuring grooves that can change the fan exhaust nozzle's cross-sectional area, allowing for increased airflow during specific flight conditions, reducing noise and improving fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the nacelle size is increased to support large diameter fans for high bypass turbofan efficiency, then propulsive efficiency is improved, but weight, noise and drag increase
Solution Approach 1:
The core cowl is designed with movable panels that can dynamically adjust the cross-sectional area of the core exhaust nozzle. This dynamic adjustment capability allows the engine to optimize its performance characteristics for different flight conditions, reducing noise and drag during non-cruise operations while maintaining efficient cruise performance with the large nacelle configuration.
2Productivity
If the nacelle size is increased to support large diameter fans, then turbofan engine efficiency is improved, but device complexity increases
Solution Approach 1:
The core cowl is divided into multiple movable panels that can be independently actuated. This segmentation allows for precise control of the exhaust nozzle cross-sectional area without requiring complex overall structural changes to the nacelle. Each panel can be controlled separately to achieve the desired airflow characteristics.
3Productivity
If the cross-sectional area of the core exhaust nozzle is fixed for maximum cruise performance, then efficiency during normal cruise operation is optimized, but performance varies during diverse flight conditions
Solution Approach 1:
The core cowl panels are designed to be movable rather than fixed, enabling the cross-sectional area of the core exhaust nozzle to be dynamically adjusted. This allows the engine to adapt its performance characteristics for different flight conditions including take-off, landing, and cruise maneuver, while maintaining optimized cruise efficiency.
4Object-generated harmful factors
If the core cowl grooves are exposed to increase airflow cross-sectional area, then noise is reduced and fuel economy is improved, but device complexity increases
Solution Approach 1:
The grooves are integrated into the core cowl structure itself rather than being separate components. By taking out the groove features directly from the cowl panels and making the panels movable, the design achieves noise reduction through increased airflow cross-sectional area without requiring additional complex mechanisms or separate devices.
Data Source
AI summary
A core nacelle for a gas turbine engine, according to an exemplary aspect of the present disclosure includes, among other things, a core cowl positioned adjacent to an inner duct boundary of a fan bypass passage having an associated cross-sectional area that radially extends between a fan exhaust nozzle and the inner duct boundary. The core cowl includes at least one groove that is selectively exposed to change the cross-sectional area at an axial location of the fan exhaust nozzle.