Rotor Blade Tip Geometry for Low-Noise Vortex Suppression
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Solution Overview
Problem
Rotorcraft, such as industrial drones, produce noise due to the rotation of rotor blades, which is a drawback.
Innovation Solution
The rotor blades are designed with a blade end portion that has a leading edge angled in the rotational direction to the outer side in the radial direction, and may include protrusions, inhibiting the generation of vortices and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the rotor blade uses a conventional straight leading edge design, then the structure is simple and easy to manufacture, but noise is produced due to vortex generation at the blade end portion
Solution Approach 1:
The leading edge of the blade end portion is designed to be asymmetric relative to the rotational direction, creating a swept-back configuration that disrupts vortex formation. This asymmetric geometry changes the flow characteristics at the blade tip, reducing the pressure differential that drives vortex generation and thereby lowering noise without requiring active control systems
Solution Approach 2:
The invention addresses the two-dimensional vortex problem by introducing a third-dimensional swept-back angle to the leading edge. This dimensional modification transforms the blade end geometry from a simple straight edge to a three-dimensional surface feature that actively manages flow separation and vortex development in the radial, tangential, and axial directions
2Object-generated harmful factors
If the leading edge of the blade end portion is angled in the rotational direction, then vortex generation is inhibited and noise is reduced, but the manufacturing complexity increases
Solution Approach 1:
The invention modifies geometric parameters of the blade end portion, specifically the leading edge angle and swept-back configuration. By changing these dimensional parameters during the blade design and manufacturing process, the flow characteristics are optimized to reduce vortex generation while maintaining compatibility with conventional composite manufacturing methods
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 reduces noise production by minimizing the pressure difference between the upper and lower surfaces of the blade end portion, thereby inhibiting vortex formation.
Implementation Method 1
a pressure acting on the upper surface of the blade end portion can be increased in magnitude. Because of this, a difference between the pressure acting on the lower surface and that acting on the upper surface in the blade end portion is made small
Implementation Method 2
generation of a vortex flowing around the blade end portion from the lower surface to the upper surface can be inhibited. As a result, the generation of blade end vortex can be inhibited
Data Source
AI summary
The disclosed rotorcraft includes a rotor blade and a prime mover. The rotor blade extends in a radial direction. The prime mover is configured to rotate the rotor blade. The rotor blade includes a blade body and a blade end portion. The blade end portion is disposed on an outer side of the blade body in the radial direction. The blade end portion includes a leading edge (i.e., an edge facing the rotational direction) that tilts in a rotational direction to the outer side in the radial direction. The disclosed configuration reduces noise produced by the rotorcraft.