Marine Propeller Reverse Thrust Cup Cavitation Control
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Solution Overview
Problem
Cavitation at the trailing face of marine propeller blades during reverse operation leads to vibration and compromised reverse thrust capability in marine vehicles.
Innovation Solution
A marine propeller design featuring a reverse thrust cup on each blade, which deflects water flow and reduces cavitation, enhancing reverse thrust and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the propeller is rotated in reverse direction, then the trailing face of each blade applies forward pressure against water to propel the vehicle rearwardly, but cavitation occurs at the trailing face causing vibration and compromised reverse thrust capability
Solution Approach 1:
The patent applies a reverse thrust cup to the trailing face of each propeller blade, creating a localized structural modification with different geometric properties than the rest of the blade surface. This local quality change allows the cup to specifically address cavitation issues at the trailing face during reverse operation, while the rest of the blade maintains its original hydrodynamic characteristics for forward operation.
Solution Approach 2:
The reverse thrust cup introduces a curved, cup-like geometry to the trailing face of the blade. This curvature is designed to modify water flow patterns during reverse rotation, redirecting flow to prevent low-pressure zones that cause cavitation. The spherical or cup-shaped geometry helps maintain higher pressure at the trailing face, eliminating bubble formation while still allowing effective reverse thrust generation.
2Force
If the trailing face of each blade is used for reverse thrust generation, then forward pressure is applied against water to propel the vehicle rearwardly, but water pressure reduction causes cavitation and vibration
Solution Approach 1:
The patent converts the harmful cavitation effect into a beneficial flow control mechanism. The reverse thrust cup is positioned and shaped to utilize the natural water flow during reverse operation, redirecting it in a way that prevents cavitation. By strategically placing the cup at the trailing face, the design transforms the problematic low-pressure zone into a controlled flow path that maintains pressure and eliminates bubble formation, thereby improving reliability.
Solution Approach 2:
The reverse thrust cup acts as an intermediary structure between the water flow and the propeller blade trailing face. During reverse operation, the cup intercepts and redirects water flow before it reaches the trailing face, preventing the direct interaction that causes pressure reduction and cavitation. This intermediary element mediates the force transmission from water to blade, maintaining higher pressure while still generating effective reverse thrust.
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 reverse thrust cup minimizes cavitation and enhances the reverse thrust capability, reducing vibration and improving control during reverse operation of marine vehicles.
Implementation Method 1
cavitation of the water at the trailing face of each blade on the propeller... the water accelerates around the edges of each blade, causing a reduction in water pressure at the trailing face of the blade until the pressure of the water eventually reaches the vapor pressure of the water. Consequently, cavitation occurs at the trailing face of the blade as the water vaporizes and small bubbles of air form in the water
Data Source
AI summary
A marine propeller with reverse thrust cup includes a propeller hub, propeller blades each having a leading blade face and a trailing blade face provided on the propeller hub and a reverse thrust cup provided in the trailing blade face of each of the propeller blades.