Variable-Pitch Fan Flow Guide for Compact Turbofan Reverse Thrust
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Solution Overview
Problem
Thrust reverser systems in turbofan engines are bulky, increasing engine size and weight, and often sacrifice flow control properties to meet size and weight goals.
Innovation Solution
A turbofan engine with a variable pitch fan and a flow guide assembly that controls airflow in reverse thrust mode, using deployable nacelle components and flow control features to redirect airflow efficiently, reducing the need for friction braking and enabling a more compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional thrust reverser systems are used, then reverse thrust capability is achieved, but engine size and weight increase
Solution Approach 1:
The patent employs movable flow control surfaces and deployable nacelle components that can dynamically adjust between forward thrust and reverse thrust configurations. These dynamic elements allow the system to achieve reverse thrust capability only when needed, rather than requiring permanent bulky structures, thereby reducing overall engine weight while maintaining functional reliability.
Solution Approach 2:
The thrust reverser system is divided into multiple independent flow control surfaces and deployable components rather than a single monolithic structure. This segmentation allows for more efficient space utilization and reduces the overall weight by only deploying necessary components during reverse thrust operation, rather than carrying a complete thrust reverser system in all configurations.
2Weight of stationary object
If thrust reverser systems are minimized for weight goals, then engine weight is reduced, but flow control properties deteriorate
Solution Approach 1:
The patent implements flow control features at specific critical locations within the bypass passage, such as flow guide assemblies positioned to optimize airflow redirection. This localized approach to flow control ensures effective performance is maintained at key points without requiring comprehensive flow control throughout the entire system, thereby reducing overall weight while preserving essential flow control properties.
Solution Approach 2:
The patent introduces flow guide assemblies as intermediary components that mediate between the bypass airflow and the reverse thrust requirement. These flow guides efficiently redirect airflow without requiring the full complexity of traditional thrust reverser systems, maintaining adequate flow control properties while significantly reducing weight and complexity.
3Reliability
If bulky thrust reverser systems are used, then reverse thrust function is achieved, but nacelle size increases
Solution Approach 1:
The patent employs nested deployable components where flow control surfaces and nacelle sections are arranged to nest within each other during forward thrust configuration. During reverse thrust operation, these nested components deploy sequentially to achieve the required flow redirection. This nesting approach minimizes the nacelle size in normal operation while providing adequate reverse thrust function when needed.
Solution Approach 2:
The patent utilizes dimensional changes by deploying nacelle components in the axial direction during reverse thrust operation rather than requiring increased radial or circumferential dimensions. This allows the nacelle to maintain a compact cross-sectional area while achieving reverse thrust capability through axial deployment of flow control surfaces and intermediate openings.
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
Improves airflow control in reverse thrust mode, allowing for a more compact nacelle and reduced demand on friction braking systems.
Implementation Method 1
the flow guide assembly configured to redirect a second fluid flow from outside the bypass passage opposite the direction of travel to inside the bypass passage in the direction of travel through the intermediate opening in the reverse thrust mode
Data Source
AI summary
A turbofan engine may include a variable pitch fan rotatable about an axis and operable in a forward thrust mode by generating flow opposite a direction of travel and in a reverse thrust mode by generating flow in the direction of travel. In reverse thrust mode, a nacelle assembly defines an intermediate opening disposed aft of the variable pitch fan. A flow guide assembly is configured to guide a first fluid flow opposite the direction of travel within a bypass passage from a forward opening to an aft opening of the nacelle assembly in forward thrust mode, and to redirect a second fluid flow from outside the bypass passage opposite the direction of travel to inside the bypass passage in the direction of travel through the intermediate opening in reverse thrust mode. One or more flow channels are defined for generating at least one fluidic injection pressurized by a core.