Helical Multi-Row Propeller for Variable Advance Ratio Efficiency
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Solution Overview
Problem
Propellers achieve maximum efficiency for a narrow range of advance ratios and become inefficient when operating outside this range, leading to suboptimal performance in vehicles or systems with varying operating conditions.
Innovation Solution
A propulsion device with two or more co-rotating rows of blades arranged in a helical fashion around a common hub, where each blade is individually coupled to the hub, allowing for angular and axial offset between rows to maintain optimal advance ratio efficiency across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional single-row propeller is used, then the structure is simple and easy to manufacture, but the propeller efficiency decreases rapidly when operating outside a narrow optimal advance ratio range
Solution Approach 1:
The propeller is divided into multiple rows of blades (first row, second row, etc.) with each row containing multiple blades. This segmentation allows different blade rows to operate at different effective advance ratios, enabling the propeller to maintain efficiency across a broader range of operating conditions while keeping each individual blade relatively simple in design
Solution Approach 2:
The invention transitions from a single-row propeller configuration to a multi-row configuration arranged in a helical pattern around the rotation axis. This dimensional change from one row to multiple rows allows the propeller to exploit additional spatial dimensions (radial and axial offsets between rows) to achieve adaptability across varying advance ratios without proportionally increasing overall complexity
2Adaptability or versatility
If the propeller operates outside the optimal advance ratio range, then it can handle varying operating conditions, but the efficiency decreases rapidly
Solution Approach 1:
Different blade rows are positioned at different radial and axial locations with specific angular offsets, creating local variations in the flow conditions each blade experiences. This local quality differentiation allows each blade row to operate optimally at different advance ratios, collectively maintaining high efficiency across a broad range of operating conditions
Solution Approach 2:
The invention changes the geometric parameters of the propeller by introducing multiple blade rows with specific angular and axial offsets. This parameter change transforms the propeller from a single-configuration system to a multi-configuration system that can adapt to varying advance ratios, reducing energy loss across different operating conditions
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
Improves propeller efficiency by maintaining effective advance ratios closer to optimal levels, enhancing performance in vehicles or systems operating outside the narrow optimal range.
Implementation Method 1
the geometry of propeller blades is intentionally designed to generate a pressure difference between fluids interacting with the upstream and downstream surface of the blade. The difference in pressure acting on the surfaces of each blade generates axial force as the propeller blades rotate
Data Source
AI summary
Propulsion devices that provide increased propeller efficiency when operating outside of an optimal advance ratio are described. In one example, a propulsion device includes a hub having a curved surface extending around and along a rotation axis of the hub. The propulsion device can further include two or more rows of blades extending radially outward from the curved surface and including a first row of blades having a first blade and a second row of blades having a second blade that is angularly and axially offset from the first blade on the curved surface. A first centerline of the first blade and a second centerline of the second blade each intersect with a helical line that extends along the rotation axis of the hub. The first blade and the second blade collectively form a helical pattern of blades that projects radially outward from the curved surface along the helical line.