Multi-Stage Propeller Layout for Cavitation and Wake Reduction
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Solution Overview
Problem
Existing counter-rotating propeller propulsion systems are inefficient and provide reduced thrust when operating outside their optimized regimes, and are complex, heavy, and costly.
Innovation Solution
A propulsion system with three propellers arranged along a common axis, where two propellers rotate in opposite directions and are driven by separate motors, allowing independent speed control, to enhance efficiency and thrust over a wide operating regime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single large propeller is used, then the boat can achieve higher speed, but the propeller becomes vulnerable to damage from debris and has cavitation issues
Solution Approach 1:
The single large propeller is divided into multiple smaller propellers (first propeller and second propeller) that rotate in opposite directions. This segmentation reduces the vulnerability of each individual propeller to debris damage and cavitation while maintaining the overall thrust capability for high-speed performance.
2Speed
If a single large propeller is used, then the boat can achieve higher speed, but the propeller generates excessive wake and spray
Solution Approach 1:
The single large propeller is segmented into multiple smaller propellers rotating in opposite directions. This configuration distributes the water displacement across multiple smaller blades, reducing the intensity of wake and spray generation while maintaining the thrust necessary for high-speed operation.
Solution Approach 2:
The propellers are configured to rotate in opposite directions, creating counterbalancing forces that reduce the net wake and spray generation. The opposing rotation directions help cancel out harmful water disturbances while maintaining effective propulsion.
3Reliability
If counter-rotating propellers are used to reduce wake and improve reliability, then propeller durability and wake reduction are improved, but the device complexity increases
Solution Approach 1:
Multiple propellers are combined into a single integrated propeller assembly that functions as one unified propulsion unit. This merging approach maintains the reliability and wake-reduction benefits of counter-rotating propellers while simplifying the overall system structure compared to separate independent propeller systems.
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 system achieves increased thrust and efficiency with reduced weight and complexity by utilizing three propellers with varying diameters and independent motor control, optimizing performance across a broader flight range.
Implementation Method 1
a first propeller and a second propeller arranged along a rotational axis of the drive shaft, each having a number of blades configured to generate thrust forces in a direction of movement of the boat when rotating in opposite directions
Implementation Method 2
configured to capture an air flow generated by the rotating propellers, wherein the hollow hub comprises a number of channels configured to direct the air flow to respective locations of the first propeller and the second propeller
Implementation Method 3
wherein the hollow hub is configured to create a low-pressure region in the air flow passing through the hollow hub
Data Source
Figure 1~2
Figure 3~4
AI summary
A propulsion system (50) is disclosed. The propulsion system (50) includes a first propeller (52), a second propeller (54), and a third propeller (56). The first propeller (52), the second propeller (54), and the third propeller (56) are arranged to rotate about a common axis and the second propeller (54) is disposed between the first propeller (52) and the third propeller (56). The first and third propellers (52, 56) are configured to rotate about the common axis in a first direction (A) and the second propeller (54) is configured to rotate about the common axis in a second direction (B) opposite to the first direction (A). A first motor (60) may be coupled to the first and third propellers (52, 56) and a second motor (64) may be coupled to the second propeller (54). A first shaft (58) and second shaft (62) may be arranged along the common axis, wherein the first and third propellers (52, 56) are coupled to the first shaft (58) and the second propeller (54) is coupled to the second shaft (62).