Hydro Generator Rotor Hub Diameter and Blade Aspect Ratio
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Solution Overview
Problem
Existing hydro-powered electricity generators face issues with blade breakage due to high operating loads and extreme bending moments in turbulent fluid flows, primarily because of the high aspect ratio and small diameter hub design of their rotors, which limits power generation capacity and increases maintenance costs.
Innovation Solution
A rotor design featuring a larger diameter hub with shorter, stronger blades of lower aspect ratio, where the blade tips to hub diameter ratio is between 1.2:1 and 2:1, concentrating energy flow and reducing stress on the blades, allowing for efficient power extraction and improved structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the rotor uses a small diameter hub with long and slender blades (high aspect ratio), then the generator has lower installation cost, but the blades are prone to breakage due to high operating loads and extreme bending moments
Solution Approach 1:
The patent changes the geometric parameters of the rotor by increasing the hub diameter and decreasing the blade length, resulting in a lower aspect ratio. This parameter change fundamentally alters the stress distribution and reduces bending moments on the blades, thereby improving reliability while maintaining manufacturing feasibility
Solution Approach 2:
The patent introduces a curved profile to the hub surface with a specific radius of curvature (one-sixth of the hub radius). This curvature modifies the flow pattern and stress distribution around the hub-blade junction, reducing extreme bending moments and improving blade durability without significantly increasing installation complexity
2Ease of manufacture
If the rotor uses long and slender blades with high aspect ratio, then the generator installation is less expensive, but the generation capacity is relatively low
Solution Approach 1:
By changing the aspect ratio parameter from high to low through increasing hub diameter and decreasing blade length, the patent achieves a rotor configuration that improves generation capacity. The shorter, stronger blades can extract energy more efficiently while the larger hub provides better structural support, collectively enhancing productivity
3Device complexity
If the rotor uses long blades with high aspect ratio, then the structure is simpler and cheaper to manufacture, but the blades are subject to extreme bending moments in turbulent flow
Solution Approach 1:
The patent simplifies the blade structure by reducing blade length and aspect ratio, which paradoxically improves strength. The shorter blades experience reduced bending moments and are less susceptible to turbulent flow effects, achieving both structural simplicity and enhanced strength simultaneously
Solution Approach 2:
The curved hub profile with radius equal to one-sixth of the hub radius modifies the flow field and stress distribution, reducing extreme bending moments on the blades. This geometric feature strengthens the blade-hub connection without adding structural complexity
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 enhances power generation efficiency, reduces manufacturing costs, lowers the likelihood of blade breakage, and allows for constant RPM operation independent of flow velocity, improving the rotor's survivability in turbulent environments and eliminating the need for an electrical frequency inverter drive system.
Implementation Method 1
Fluid flowing past the rotor blades causes it to rotate which in turn causes the rotation in the converter and the generation of electrical power
Data Source
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AI summary
A rotor (10) for a hydro-powered electricity generator. The rotor (10) includes a hub (12) and a plurality of blades (16). The hub (12) has a circular cross sectional shape and a longitudinal rotational axis (14). The plurality of blades (16) each have a proximal root (16a) and a distal tip (16b). Each of the blade roots (16a) are mounted to the hub (12) at the widest part thereof (D1). The ratio between the diameter of the tips (16b) of the blades to the diameter of the widest part (D1) of the hub (12) is less than about 2:1.