Divided Rotor Blade With Leading Edge Holes
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Solution Overview
Problem
Conventional rotor and propeller blades are prone to flutter, cavitation, and accelerated stalling at transonic and supersonic tip speeds due to lack of support, leading to structural failure and inefficiency, and they operate with higher drag and noise.
Innovation Solution
A divided rotor blade design with two distinct blade portions extending to a common tip, featuring a tapered gap and leading edge holes to reduce drag and prevent cavitation, turbulence, and stalling, while allowing for dissimilar angles of incidence and improved lift and thrust.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional rotor blades are made long and entirely unsupported along their length to increase thrust, then the blade area is increased, but the blade becomes subject to flutter, cavitation, and accelerated stalling at transonic and supersonic tip speeds
Solution Approach 1:
The rotor blade is divided into two separate blade portions (first and second blade portions) that are supported at different locations along the rotor shaft. This segmentation provides intermediate support along the blade length, reducing the unsupported span and preventing flutter and cavitation while maintaining the benefits of a long blade design for increased thrust.
2Strength
If conventional rotor blades have large root sections to obtain sufficient strength to prevent bending and twisting, then the structural strength is improved, but the blade weight increases
Solution Approach 1:
By dividing the blade into two portions supported at different locations, each portion can have a smaller root section while the combined structure provides the necessary overall strength. The first blade portion is supported at a first location and the second blade portion at a second location, distributing the structural load and reducing the weight requirement for any single root section.
3Weight of moving object
If conventional rotor blades have decreased chord length in the tip to reduce weight, then the blade weight is reduced, but the blade becomes subject to accelerated stalling at high angles of incidence
Solution Approach 1:
The blade portions are configured with specific geometric features including twisted configurations and angled leading and trailing edges. The first blade portion has a leading edge angled at a first angle and a trailing edge angled at a second angle, while the second blade portion has corresponding angles. This local optimization of geometry at different locations along the blade maintains stall resistance even with reduced chord length at the tip.
4Force
If divided rotor blade portions are oriented axially displaced on a shaft to increase lift, then the lift is increased, but the blade operates with higher degree of drag
Solution Approach 1:
The blade portions are twisted along their length, with the angle of incidence varying from the root to the tip. This parameter change optimizes the local angle of attack at different radial positions, maximizing lift while minimizing drag. The twisted configuration ensures that each section of the blade operates at its optimal angle, reducing overall drag while maintaining high lift 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
The design enables effective operation at supersonic tip speeds with reduced drag, increased lift, and resistance to cavitation and stalling, enhancing performance and structural integrity.
Implementation Method 1
integral leading edge holes or ports to allow medium passage through the rotor body and across the rotor chord to delay or prevent cavitation, turbulence, and stalling
Implementation Method 2
two distinct blade portions with respective roots which are separated from each other. The blade portions extend convergingly from their roots to join at a common tip
Data Source
AI summary
A novel rotor blade is presented with an integral tip portion from which two diverging blade portions extend to separated respective roots. The blade may have conventional airfoil sections, or may be made from flat or curved sheet material. The two rotor blade portions may have dissimilar angles of incidence. Leading edge holes or slots are located behind the leading edge of the blade. The two blade portions may have distinct angles of incidence.