Gate Rudder Structure for Propeller Efficiency and Cavitation Control
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Solution Overview
Problem
Existing gate rudder technologies fail to achieve sufficient rudder force for straight travel, leading to high energy consumption and require large steering machines due to small rudder area, and are prone to cavitation erosion.
Innovation Solution
A gate rudder design with horizontal and vertical rudder portions, optimized rudder shaft placement, and clearance between the propeller and rudder, along with torsion angles, to enhance Coanda and USB effects for reduced energy consumption and prevent cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the clearance between the propeller and the left and right rudders is set to be small in order to increase the efficiency of the propeller, then the propeller efficiency is improved, but cavitation erosion easily occurs on the inner faces of the left and right rudders
Solution Approach 1:
The patent applies different clearance values to different parts of the rudder structure. Specifically, the clearance between the propeller and the first rudder portion is set to 0.04D to 0.1D, while the clearance between the propeller and the second rudder portion is set to 0.01D to 0.03D. This local differentiation allows the first rudder portion to be protected from cavitation erosion while the second rudder portion maintains close proximity to the propeller for high efficiency.
2Area of moving object
If a left rudder and a right rudder extending in the front-rear direction with a predetermined distance are provided left and right, respectively, of a propeller, then the rudder area is reduced, but a large torque is generated requiring substantially the same capacity of the steering machine as in the related art
Solution Approach 1:
The patent transitions from a conventional single-plane rudder to a three-dimensional gate rudder structure with rudders extending both laterally and axially from the propeller. The first rudder portions extend laterally with larger area, while the second rudder portions extend axially. This spatial redistribution reduces the torque required for steering while maintaining adequate rudder area for effective control.
3Use of energy by moving object
If the rudder chord length and propeller position are optimized to generate large thrust force through Coanda and USB effects, then energy consumption is reduced, but the rudder structure becomes more complex
Solution Approach 1:
The gate rudder is divided into multiple segments: first rudder portions extending laterally and second rudder portions extending axially. Each segment serves a specific function in generating thrust through the Coanda and USB effects. The propeller is positioned at 0.15L to 0.65L from the front edge of the second rudder portion, creating optimized flow interaction. This segmentation allows complex aerodynamic effects to be achieved through modular structural elements.
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 design generates large thrust forces for forward motion, minimizes torque, and prevents cavitation, optimizing steering machine capacity and reducing energy consumption across various ship types.
Implementation Method 1
sufficient rudder force due to the Coanda effect and the upper surface blowing (hereinafter, it is referred to as a USB.) effect
Implementation Method 2
sufficient rudder force due to the Coanda effect and the upper surface blowing (hereinafter, it is referred to as a USB.) effect
Data Source
AI summary
To provide a gate rudder capable of reducing energy consumption during a voyage of a ship.A gate rudder including a pair of rudders including a left rudder and a right rudder disposed left and right, respectively, of a propeller at a stern, wherein each of the rudders includes a first rudder portion extending in a horizontal direction and a second rudder portion linearly extending in a vertical direction in rear view, wherein a rudder chord length of the second rudder portion in a front-rear direction is 40 to 100% of a diameter of the propeller, wherein the propeller is provided within a range of 15 to 65% of the rudder chord length from a front edge of the second rudder portion in side view, and wherein a rudder shaft that drives each of the rudders is provided at a position within a range of 30 to 50% of the rudder chord length from the front edge of the second rudder portion in side view.