Segmented Nacelle Cowl Design for High Bypass Engine Drag Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional high bypass ratio engine nacelles require significant clearance between the engine and the nacelle, increasing size and drag, and limiting the positioning of the nacelle relative to the wing, which affects thrust efficiency and fuel consumption.
Innovation Solution
The implementation of a splitter cowl that radially offsets the bypass air flow, dividing it into multiple paths, reducing the outer profile of the nacelle and allowing for a smaller thrust reverse structure, along with blocker doors to manage thrust and pressure, enabling cost and weight savings and improved clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional high bypass ratio engine nacelles are designed with sufficient clearance between the engine and nacelle, then engine accessibility and maintenance are improved, but the nacelle size increases and drag forces increase
Solution Approach 1:
The nacelle is divided into multiple cowls (first cowl, second cowl, third cowl) that can be independently accessed and maintained. The splitter cowl creates separate flow paths that allow maintenance personnel to access engine components from multiple directions without requiring excessive overall clearance, thereby reducing drag while maintaining accessibility.
Solution Approach 2:
The patent introduces a radial dimension by offsetting the second cowl radially from the first cowl and creating multiple flow paths (first flow path radially outward, second flow path between first flow path and engine core). This multi-dimensional arrangement allows maintenance access from different spatial directions while minimizing the nacelle's overall cross-sectional area and drag profile.
2Loss of energy
If the nacelle cross-sectional area is reduced to minimize drag, then fuel consumption is improved, but clearance between the engine and nacelle is reduced
Solution Approach 1:
The nacelle is segmented into multiple cowls with separate access paths. The first cowl, second cowl, and third cowl can be independently removed or accessed, allowing maintenance personnel to reach engine components through multiple routes. This segmentation enables smaller overall clearance while maintaining adequate access to engine parts for maintenance activities.
Solution Approach 2:
The nacelle incorporates movable components including blocker doors that can be positioned in different locations (first blocker door position, second blocker door position) to control flow paths and provide dynamic access to engine components. This dynamic adjustment allows the system to maintain both compact size and maintenance accessibility under different operational conditions.
3Productivity
If multiple flow paths are created to improve thrust efficiency, then engine performance is improved, but nacelle structural complexity increases
Solution Approach 1:
The nacelle structure is segmented into distinct cowls (first cowl, second cowl, third cowl) that naturally define separate flow paths. The splitter cowl divides the airflow into a first flow path radially outward and a second flow path between the first flow path and engine core. This segmentation creates multiple thrust-generating flow paths while using modular structural elements that can be manufactured and assembled independently, managing overall complexity.
Solution Approach 2:
The cowls and splitter cowl serve multiple functions: they define flow paths for thrust generation, provide structural support, enable maintenance access, and control airflow distribution. By making these components multi-functional, the patent achieves improved thrust efficiency through multiple flow paths without proportionally increasing structural complexity, as the same elements perform multiple roles.
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
This configuration reduces drag, allows for higher nacelle positioning relative to the wing, and enables the use of larger diameter fans, enhancing thrust efficiency and fuel efficiency while minimizing the nacelle's cross-sectional area.
Implementation Method 1
The fan may be configured to conduct an airflow through a portion of the outer cowl and the splitter cowl
Implementation Method 2
The second cowl may be configured to separate a flow of air passing through the fan into at least a first flow path and a second flow path
Data Source
AI summary
Nacelle air management systems for a high bypass ratio engine are provided. The nacelles air management systems may include an outer cowl and an inner cowl that are configured to provide dual bypass flow channels around an engine core. These systems may be employed to accommodate larger engine fans. The nacelle air management system may also include one or more blocker doors are configured to at least partial obstruct and/or direct air from the dual bypass flow channels to create reverse thrust.