Ducted Fan Blade Geometry for Higher Static Thrust
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Solution Overview
Problem
Existing ducted fan designs struggle to maximize static thrust, particularly in cases with high disc loading, as conventional methods for determining propeller blade shapes are not applicable and lead to inefficiencies in thrust calculation and vortex management.
Innovation Solution
A ducted fan design featuring a round-shaped lip at the intake port and blades with a chord length that gradually decreases toward the tip, increasing again near the tip, minimizing energy loss and enhancing flow uniformity, which maximizes static thrust by optimizing the flow rate and reducing vortex-induced energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional propeller blade shapes are used in ducted fans, then manufacturing is simpler, but static thrust cannot be maximized due to inefficiencies in vortex management and energy loss
Solution Approach 1:
The blade is designed with non-uniform chord length distribution where the chord length gradually decreases from root to tip, then increases again near the tip. This local variation in blade geometry optimizes the aerodynamic properties at different radial positions, reducing vortex-induced energy loss and maximizing static thrust generation.
Solution Approach 2:
The blade chord length is designed to dynamically vary along the span, creating an optimized flow pattern that adapts to the rotational motion and pressure distribution. This dynamic geometric configuration minimizes energy loss while maximizing thrust production.
2Productivity
If blade chord length is uniformly distributed, then manufacturing is easier, but flow uniformity inside the duct deteriorates leading to reduced thrust efficiency
Solution Approach 1:
The blade employs a non-uniform chord length distribution that varies locally along the span. The chord length gradually decreases toward the tip and then increases near the tip, creating optimized local flow characteristics that collectively improve overall flow uniformity inside the duct and enhance thrust efficiency.
3Force
If blade tip is positioned away from the duct inner wall, then manufacturing and assembly are easier, but vortex-induced energy loss increases reducing thrust
Solution Approach 1:
The blade tip is positioned adjacent to the duct inner wall to convert the potentially harmful vortex flow into beneficial flow patterns. This configuration reduces vortex-induced energy loss by utilizing the duct wall to control and redirect the vortex flow, transforming what would be a loss mechanism into a thrust-enhancing feature.
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 achieves a significant increase in static thrust while maintaining structural strength and reducing noise, making it suitable for multicopters, vertical take-off and landing aircraft, CPU-cooling fans, and radiator-cooling fans.
Implementation Method 1
substantially no vortices go through a gap therebetween and energy loss due to vortices lowers
Implementation Method 2
the flow rate of the outer board of the inside of the duct increases
Implementation Method 3
thrust based on upward suction produced in accordance with the flow rate of the flow going around the round-shaped lip of the duct increases
Data Source
AI summary
[Object] To maximize static thrust of a ducted fan. [Solving Means] This ducted fan 1 includes a duct 10, a fan 20, a motor 30, a housing 40, and stators 50. The fan 20 includes a hub 21 disposed concentric with the duct 10 and four blades 22 arranged at equal intervals on the outer circumference of the hub 21. A chord length CL of the blade 22 gradually decreases toward a tip 22A from the root. In contrast, the chord length CL of the blade 22 increases to the tip 21B from a tip vicinity portion 22B.