Split Cowl Nozzle Assembly for Turbofan Engine Efficiency
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Solution Overview
Problem
Turbofan engine nozzle assemblies face challenges in efficiently regulating airflow through the fan duct area to optimize engine performance and reduce noise and fuel burn during varying flight conditions, such as take-off and descent.
Innovation Solution
A split cowl assembly with repositionable arcuate portions is used to vary the throat area of the fan nozzle duct, allowing for improved engine efficiency and noise reduction by altering the bypass fan duct area, which is achieved by positioning the arcuate portions within the bypass fan duct to change the duct area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed fan nozzle duct area is used, then the structure is simple and lightweight, but engine efficiency cannot be optimized across varying flight conditions
Solution Approach 1:
The patent applies the dynamics principle by making the fan nozzle duct area adjustable rather than fixed. The split cowl assembly with repositionable arcuate portions allows the nozzle area to be dynamically changed based on flight conditions, enabling optimization of engine efficiency during different operating phases such as take-off, cruise, and descent.
Solution Approach 2:
The patent applies segmentation by dividing the cowl assembly into separate repositionable arcuate portions. This segmentation allows independent adjustment of different sections of the nozzle, providing flexible control over the fan nozzle duct area while maintaining structural manageability.
2Loss of energy
If the fan nozzle duct area is reduced to improve efficiency at certain operating speeds, then fuel burn is reduced, but noise from fan wake/OGV interaction increases
Solution Approach 1:
The patent uses dynamic adjustment of the fan nozzle duct area to balance fuel efficiency and noise reduction. By repositioning the arcuate portions of the split cowl assembly, the system can optimize the nozzle area for fuel efficiency during cruise while maintaining higher noise levels only when necessary, rather than permanently increasing noise.
3Device complexity
If a translating core cowl is used as a thrust reverser without blocker doors, then the device complexity is reduced, but the fan nozzle duct area control is limited
Solution Approach 1:
The patent applies segmentation by splitting the cowl assembly into repositionable arcuate portions, which provides versatile control over the fan nozzle duct area. This segmented design allows independent adjustment of different sections, enhancing adaptability while maintaining relatively simple device complexity.
Solution Approach 2:
The patent applies multi-functionality by designing the split cowl assembly to serve multiple purposes: it functions as both a thrust reverser mechanism and a fan nozzle duct area control system. This universal design eliminates the need for separate blocker doors while providing comprehensive control over airflow and nozzle area.
Data Source
AI summary
A method for operating a turbofan engine assembly including a core gas turbine engine is provided. The method includes varying an operating speed of the turbofan engine assembly from a first operating speed to a second operating speed. The method also includes selectively positioning a first arcuate portion and a second arcuate portion of a split cowl assembly to vary a throat area of a fan nozzle duct defined downstream from the core gas turbine engine to facilitate improving engine efficiency at the second operating speed. The split cowl assembly is downstream from the core gas turbine engine and inside the fan nozzle duct. A turbofan engine assembly and nozzle assembly are also provided.