Cross-flow fan wing propulsion with perpendicular rotor axis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional cross-flow fan designs for aircraft propulsion systems face challenges such as low propulsive efficiency, high parasite drag, and flow separation at high angles of attack, due to poor fan placement and housing design, which limits their effectiveness in producing thrust and circulation control.
Innovation Solution
A distributed cross-flow fan wing design with a housing, rotor compartment, and outlet configuration where the rotor rotates about a perpendicular axis, allowing air to flow in along one longitudinal axis and exhaust along a parallel axis, effectively capturing airflow and reducing vortex effects, and incorporating a movable deflector for enhanced lift and drag control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional HVAC-type cross-flow fan housing is used with 90 degree turn from inlet to outlet, then the fan can handle flow distortion and provide high pressure coefficient, but the propulsor cannot ingest and expel flow in a linear manner to produce forward thrust
Solution Approach 1:
The housing is divided into distinct functional sections: an inlet section, a rotor compartment, and an outlet section. This segmentation allows each part to be optimized for its specific function - the inlet captures flow distortion, the rotor compartment houses the cross-flow fan, and the outlet directs flow linearly for thrust production, resolving the contradiction between pressure coefficient and thrust capability
Solution Approach 2:
The housing transitions from a conventional 90-degree turn configuration to a linear inlet-to-outlet arrangement. By changing the spatial dimension and orientation of the flow path, the design enables linear thrust production while maintaining the cross-flow fan's ability to handle flow distortion and generate pressure coefficient
2Volume of moving object
If cross-flow fans are embedded within the middle of a conventional airplane wing or near the trailing edge with shafts and couplings, then the fan size and ducting are limited, but the designs result in low fan performance, reduced circulation control, and low thrust production
Solution Approach 1:
The housing is merged with the aircraft wing structure, integrating the propulsion system into the wing itself. This merging eliminates the need for separate shafts and couplings, removes the limitations on fan size, and enables the cross-flow fan to achieve high thrust production while maintaining compact dimensions
Solution Approach 2:
The housing serves multiple functions simultaneously: it acts as the propulsion system housing, integrates with the wing structure, provides flow distribution, and enables circulation control. This multi-functionality resolves the contradiction by eliminating the need for separate components that would limit fan size and performance
3Ease of operation
If conventional propulsor designs with engine pylon and nacelle support structure are used, then the propulsor can be externally mounted, but the aircraft parasite drag is increased by 18 to 20%, reducing cruise efficiency and range
Solution Approach 1:
The propulsion system is merged with the wing structure, eliminating the need for separate engine pylons and nacelle support structures. This integration removes the source of additional parasite drag while maintaining ease of operation through the embedded cross-flow fan design
Solution Approach 2:
The harmful support structures (engine pylon and nacelle) are extracted from the design. By removing these unnecessary components and integrating the propulsion system directly into the wing, the design eliminates the associated parasite drag while preserving operational capability
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 design achieves high propulsive efficiency, reduced parasite drag, and minimized flow separation at high angles of attack, enabling short takeoff and landing capabilities and low in-flight stall speeds without additional high-lift devices, while also eliminating the need for control surfaces and reducing drag from external propulsor structures.
Implementation Method 1
The cross-flow fan (CFF), developed in 1893 by Mortier, is used extensively in the HVAC industry. The fan is usually long in relation to the diameter, so the flow approximately remains 2-dimensional (2D). The CFF uses an impeller with forward curved blades, placed in a housing consisting of a rear wall and vortex wall.
Implementation Method 2
a housing defining an inlet, a rotor compartment, and an outlet, with the inlet adapted to receive an inflow of air along a first longitudinal axis; a rotor mounted within the rotor compartment and adapted to receive the airflow introduced into said housing through the inlet and rotate about a second longitudinal axis that is substantially perpendicular to the first longitudinal axis; and an outlet adapted to receive the airflow processed through the rotor and exhaust air along a third longitudinal axis that is substantially parallel to the first longitudinal axis
Data Source
AI summary
A cross-flow propulsion mechanism for use in providing propulsion to an aircraft, includes a housing defining an inlet, a rotor compartment, and an outlet. The inlet is adapted to receive an inflow of air along a first longitudinal axis. The rotor is mounted within the rotor compartment and adapted to receive the airflow introduced into the housing through the inlet and rotate about a second longitudinal axis that is substantially perpendicular to the first longitudinal axis. The outlet is adapted to receive the airflow processed through the rotor and exhaust air along a third longitudinal axis that is substantially parallel to the first longitudinal axis. The propulsion mechanism can be applied in a personal aircraft, an STOL aircraft, and a hybrid automobile and aircraft.