Ducted Fan Hub Segmentation for Propulsion Efficiency
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Solution Overview
Problem
Aircraft propulsion devices with ducted fans face reduced propulsion efficiency due to air resistance from the hub and decreased effective area for fan blades, leading to lower propulsion force.
Innovation Solution
A propulsion device design featuring a duct with an airfoil cross-sectional shape, an outer peripheral ring, fan blades extending from this ring, and an inner peripheral ring with an air flow passage, allowing for increased mass flow rate and reduced air resistance, enhancing propulsion efficiency and force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a motor is built in the hub, then the propulsion device can be compact and integrated, but the hub becomes a source of air resistance and reduces propulsion force
Solution Approach 1:
The invention extracts the motor from the hub structure and places it in a separate mounting position. The hub is reduced to only the functional elements needed for blade support (spokes and rim), eliminating the motor housing and other components that created air resistance. This separation allows the hub to be minimalistic while the motor is mounted externally or in an optimized position.
Solution Approach 2:
The propulsion device is segmented into distinct functional components: the hub structure (spokes and rim) is separated from the motor assembly. This segmentation allows each component to be optimized independently - the hub for minimal air resistance and the motor for efficient power delivery, resolving the contradiction between integration and performance.
2Strength
If a hub is provided, then the fan blades can be supported structurally, but the effective area occupied by fan blades decreases and air flow rate reduces
Solution Approach 1:
The hub is segmented into discrete spokes radiating from the center to the rim, rather than a solid continuous structure. This segmentation dramatically reduces the projected area of the hub while maintaining structural support through the spoke elements, allowing fan blades to occupy maximum effective area.
Solution Approach 2:
The hub structure uses thin spoke elements and a minimal rim rather than a bulky solid structure. These thin film-like structures provide necessary structural support with minimal interference to the air flow and effective blade area.
3Ease of operation
If a hub is provided, then the fan blades can be mounted, but air resistance increases and propulsion efficiency decreases
Solution Approach 1:
The motor is extracted from the hub structure and mounted separately, eliminating the bulky motor housing that contributed to air resistance. The hub retains only the essential spoke-and-rim structure for blade mounting, minimizing energy loss from drag while preserving ease of operation.
Solution Approach 2:
The hub design prioritizes aerodynamic efficiency by using a minimal structure that still provides adequate blade mounting capability. The dynamic performance is optimized by reducing static drag elements, allowing the system to operate more efficiently during rotation.
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 design increases propulsion efficiency by reducing power required per unit thrust and minimizing air resistance, while improving propulsion force through optimized air flow management within the device.
Implementation Method 1
Air flow is generated from the front side toward the rear side of the duct by rotating the fan blades by the motor
Implementation Method 2
an inner peripheral ring formed in a annular shape being connected radially inner end portions of the plurality of fan blades and in which an air flow passage is formed so that air flows therethrough in the direction of the axis
Data Source
AI summary
A propulsion device includes: a duct in which a flow path extending in a direction of an axis; a fan which is provided with a) an outer peripheral ring formed in an annular shape surrounding the axis and installed to be relatively rotatable around the axis with respect to the duct, b) a plurality of fan blades arranged at intervals in a circumferential direction such that each blade is extended from the outer peripheral ring toward the inside of the flow path, and c) an inner peripheral ring formed in an annular shape being connected radially inner end portions of the plurality of fan blades and in which an air flow passage is formed so that air flows therethrough in the direction of the axis; and a motor which drives the fan to rotate around the axis.