Ship Propeller Nozzle Recessed Anode Design
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Solution Overview
Problem
Existing ship propeller nozzles suffer from electrolytic corrosion when used in seawater, leading to premature wear and reduced efficiency due to the presence of sacrificial anodes which increase drag and disrupt fluid flow.
Innovation Solution
A nozzle design featuring recessed receptacles on the outer surface to house sacrificial anodes, allowing for a large number of anodes to be arranged without protruding, thus minimizing flow disruption and enabling easy replacement, with an electrically conductive carrier plate for effective corrosion protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sacrificial anodes are mounted on the outer surface of the nozzle shroud for corrosion protection, then corrosion resistance is improved, but nozzle drag increases and thrust is reduced
Solution Approach 1:
The sacrificial anodes are nested within a recessed receptacle in the nozzle jacket, allowing them to be housed inside the nozzle structure rather than protruding from the outer surface. This nesting approach provides corrosion protection while minimizing disruption to the fluid flow and reducing drag losses.
2Reliability
If multiple sacrificial anodes are arranged on the nozzle surface, then corrosion protection is improved, but the disruption to fluid flow and drag increase
Solution Approach 1:
Multiple sacrificial anodes are nested within the recessed receptacle, allowing sufficient corrosion protection volume while maintaining a streamlined outer surface that minimizes flow disruption and preserves nozzle thrust.
Solution Approach 2:
The receptacle is positioned in the rear region of the nozzle, utilizing the axial dimension to house the anodes away from the critical flow regions, thereby reducing their impact on fluid flow and thrust generation.
3Reliability
If sacrificial anodes are attached to the nozzle for corrosion protection, then reliability is improved, but manufacturing complexity and replacement difficulty increase
Solution Approach 1:
The nozzle system is segmented into the nozzle jacket with an integrated receptacle and separate sacrificial anodes. This segmentation allows the nozzle to be manufactured as a complete unit with the receptacle already formed, while the anodes can be independently replaced when consumed.
Solution Approach 2:
The receptacle is preliminarily formed as an integral part of the nozzle jacket during nozzle manufacturing. This preliminary action eliminates the need for separate mounting structures and simplifies both the manufacturing process and future anode replacement procedures.
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 maintains nozzle thrust and efficiency while providing effective corrosion protection, allowing for easy anode exchange and reduced drag, enhancing the overall performance and longevity of the propulsion system.
Implementation Method 1
the nozzle shroud is usually made of metal and must be protected against electrolytic corrosion. Otherwise, particularly when the ship's propeller is used in seawater, there is a risk of severe electrolytic corrosion
Implementation Method 2
there is a risk of severe electrolytic corrosion and the resulting premature wear of components of the propulsion system comprising the ship's propeller, including the associated nozzle, due to the high conductivity of seawater and its suitability as an electrolyte and galvanic cell
Data Source
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AI summary
The invention relates to a nozzle (1) of a ship propeller (19) that can rotate about an axis of rotation (A), comprising a nozzle casing (10) extending along the axis of rotation (A) and surrounding the ship propeller (19), and having inner and outer surfaces (11, 12), which together form a flow profile, and having at least one sacrificial anode (2) arranged on the outer surface (12) of the nozzle casing (10), wherein the outer surface (12) of the nozzle casing (10) has at least one recess (13) that is deepened in relation to the flow profile and the at least one sacrificial anode (2) is correspondingly designed such that it can be introduced into the recess (13) such that it substantially fills the recess (13).