Ship Rudder Flow Body for Cavitation and Turbulence Control
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Solution Overview
Problem
Existing ship rudders with twisted designs face challenges in preventing cavitation-induced erosion and turbulence, particularly when used in fast ships with heavily loaded propellers, and the addition of Costa bulbs can negatively impact propulsion behavior and increase fuel consumption.
Innovation Solution
A flow body is integrated into the rudder at the transition area between offset leading or trailing edges, designed to cover these surfaces and minimize protrusion, thus reducing turbulence and maintaining propulsion efficiency without affecting the ship's propulsion system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If twisted rudder design with offset leading edges is used, then cavitation protection and erosion prevention are improved, but turbulence and flow separation occur in the transition area
Solution Approach 1:
A flow body is introduced as an intermediary element in the transition area between offset leading edges. This flow body smooths the flow transition, eliminating turbulence and flow separation while preserving the cavitation protection benefits of the twisted rudder design.
Solution Approach 2:
The flow body features a curved, streamlined shape that replaces the sharp angular transition between offset leading edges. This curvature promotes smooth flow attachment and eliminates the turbulence generated by abrupt geometric changes.
2Object-affected harmful factors
If Costa bulbs are added to twisted rudders, then cavitation protection is improved, but propulsion behavior is negatively impacted and fuel consumption increases
Solution Approach 1:
The invention extracts only the essential flow-smoothing function from the Costa bulb concept, implementing a simplified flow body that provides cavitation protection through localized flow management without the excessive protrusion that negatively impacts propulsion efficiency and increases fuel consumption.
3Object-generated harmful factors
If flow body is designed to cover offset surfaces, then turbulence is reduced, but protrusion into propeller jet area may occur
Solution Approach 1:
The flow body is designed with non-uniform geometry, featuring maximum coverage of the offset surfaces where turbulence occurs, while tapering to minimal protrusion in regions where it would interfere with the propeller jet. This localized quality optimization balances turbulence reduction with propulsion efficiency.
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 flow body reduces the risk of cavitation and turbulence while maintaining propulsion efficiency, allowing for easy integration with existing rudders without complex testing, and does not negatively impact the ship's fuel consumption or propulsion behavior.
Implementation Method 1
The 60 shows an embodiment of a rudder according to the invention... adapted to the spin in the propeller jet through the offset arrangement of the front leading edges of the two rudder blade sections. With such rudders, the offset arrangement of the front leading edges and the rear trailing edges and the resulting sharp transitions between the edges of the individual rudder blade sections can lead to turbulence in the flow, which, among other things, increases the risk of cavitation.
Implementation Method 2
the offset arrangement of the front leading edges and the rear trailing edges and the resulting sharp transitions between the edges of the individual rudder blade sections can lead to turbulence in the flow
Data Source
Figure 1a~1d
Figure 2a~2d
Figure 3~3b
AI summary
The rudder (200) has a slim profile provided with a small profile thickness with maximum suspension rudder blade (100) that are made of two rudder blade sections (10,20) arranged lying one upon another. Two leading edges (11,21) and a trailing edge (15) are provided, which run under deduction of the cross-section areas from an upper area (OB) to a lower area (UB) of the rudder blade. The distance between that flat arc-shaped running side panel sections is larger than the distance between the thick arc-shaped running side panel sections.