Distributed Boundary Layer Fans for Aircraft Drag Reduction
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Solution Overview
Problem
Conventional aircraft propulsion systems face challenges in reducing drag and improving propulsive efficiency due to the interaction of turbofan jet engines with freestream airflows, which are not effectively addressed by existing boundary layer ingestion systems.
Innovation Solution
An aircraft equipped with a distributed fan array mounted circumferentially around the aft end of the fuselage, featuring fans of varying sizes and independently controlled by electric machines to ingest boundary layer airflow, minimizing drag and optimizing thrust output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a single large boundary layer ingestion fan is used, then the drag reduction effect is significant, but the device complexity and maintenance difficulty increase
Solution Approach 1:
The patent divides a single large boundary layer ingestion fan into multiple smaller fans distributed around the fuselage. Each fan independently ingests boundary layer airflow from different locations, achieving cumulative drag reduction while simplifying individual fan design and maintenance requirements
Solution Approach 2:
The patent combines multiple small fans into a coordinated system that works together to ingest boundary layer airflow. The fans are controlled in unison or coordination to achieve the drag reduction effect of a single large fan while maintaining the advantages of smaller, simpler individual units
2Adaptability or versatility
If fans are distributed around the fuselage, then adaptability to different fuselage shapes is improved, but the device complexity increases
Solution Approach 1:
The patent segments the boundary layer ingestion function across multiple fan locations around the fuselage. This segmentation allows each fan to be sized and positioned according to local boundary layer characteristics, improving adaptability to different fuselage shapes and sizes
Solution Approach 2:
The patent applies local quality by positioning fans at specific locations around the fuselage where boundary layer airflow is most beneficial to ingest. Each fan's size and orientation can be optimized for its local position, enhancing overall system adaptability while maintaining manageable complexity
3Power
If fans of different sizes are used, then optimization of thrust output is improved, but the ease of manufacture decreases
Solution Approach 1:
The patent employs different sized fans at different locations around the fuselage to optimize thrust output. Larger fans are positioned where greater boundary layer ingestion is beneficial, while smaller fans are used where less ingestion is needed, maximizing overall propulsion efficiency
Solution Approach 2:
The patent segments the fan system into different size categories, allowing for optimized performance while potentially using standardized fan designs within each size category to maintain ease of manufacture
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
The system enhances propulsive efficiency by reducing drag and improving thrust management, allowing for flexible operation and easier maintenance of fans, while effectively handling various fuselage shapes and wake profiles.
Implementation Method 1
boundary layer airflow flowing along the fuselage
Implementation Method 2
The fans are positioned so as to ingest boundary layer airflow flowing along the fuselage
Data Source
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AI summary
An aircraft (100) having distributed fans (212, 222, 232, 242, 252) for boundary layer ingestion is provided. In one aspect, an aircraft includes a fuselage extending between a forward end and an aft end. The aircraft includes a plurality of boundary layer ingestion fans (212, 222, 232, 242, 252) arranged in an array. Each fan of the array is mounted to and arranged circumferentially around the aft end of the fuselage. The fans are positioned so as to ingest boundary layer airflow flowing along the fuselage. At least two fans (222, 232) of the array are different sizes. Each fan of the fan array is operatively coupled with an electric machine (214, 224, 234, 254). The electric machines are operable to drive their respective fans to produce thrust. The fans of the array are independently controlled in accordance with the boundary layer suction requirements of the aircraft (100).