Submarine Inline Thruster for Low-Speed Maneuverability
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Solution Overview
Problem
Military submarines face challenges in maneuverability at low speeds due to rudder systems that develop a rudder effect only at high speeds and produce significant acoustic signatures when auxiliary drives like bow thrusters are used, affecting handling characteristics and stealth capabilities.
Innovation Solution
A submarine equipped with an inline thruster as an auxiliary drive, which can be moved from a rest position between the pressure hull and outer skin to a working position outside, providing efficient propulsion with a low acoustic signature, allowing for maneuverability in confined spaces or low-speed operations without compromising the submarine's stealth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a rudder system is used for steering the submarine, then the submarine can be steered during normal operation, but the rudder system only develops a rudder effect at relatively high minimum speeds and produces large turning radii
Solution Approach 1:
The auxiliary propulsion system is designed to be movable between a stowed position and an operational position, allowing the submarine to dynamically adapt its propulsion configuration based on speed requirements. At low speeds, the auxiliary propeller provides direct thrust for precise maneuvering, while at higher speeds it can be stowed to reduce drag.
Solution Approach 2:
The propulsion system is segmented into a main propeller for high-speed operation and a separate auxiliary propeller for low-speed maneuvering. This segmentation allows each propeller to be optimized for its specific speed range, with the auxiliary propeller providing effective thrust at low speeds where the main propeller is less efficient.
2Ease of operation
If bow thrusters are used as auxiliary propulsion for low-speed maneuvering, then the vessel becomes more maneuverable, but the handling characteristics deteriorate during normal operation and acoustic signature increases
Solution Approach 1:
The auxiliary propeller is designed to be movable between a stowed position within the pressure hull and an operational position extending through the outer skin. This dynamic reconfiguration allows the system to provide auxiliary propulsion only when needed for low-speed maneuvering, while remaining hidden during normal operation to minimize acoustic signature and flow restriction.
Solution Approach 2:
The auxiliary propeller is extracted from the pressure hull and positioned in the water-flooded space between the pressure hull and outer skin when not in use. This extraction removes the propeller from the hydrodynamic flow path during normal operation, eliminating flow restriction and associated acoustic noise, while allowing easy deployment when auxiliary propulsion is required.
3Ease of operation
If the auxiliary drive is always mounted outside the outer skin, then maneuverability is improved, but the acoustic signature increases during normal operation
Solution Approach 1:
The auxiliary propeller system is designed with dynamic positioning capability, allowing it to be moved between a stowed position within the pressure hull and an operational position extending through the outer skin. This dynamic reconfiguration enables the system to provide auxiliary propulsion only when needed for low-speed maneuvering, while remaining hidden during normal operation to minimize acoustic signature and flow restriction.
4Ease of operation
If shaft or rod passages are provided through the pressure hull for the auxiliary drive, then the auxiliary drive can be operated, but the pressure hull structure is weakened and sealing becomes complex
Solution Approach 1:
The auxiliary propeller is extracted from the pressure hull and positioned in the water-flooded space between the pressure hull and outer skin. This extraction eliminates the need for shaft or rod passages through the pressure hull, maintaining structural integrity and simplifying sealing requirements. The auxiliary propeller can still be operated effectively from this external position.
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 inline thruster enhances maneuverability at low speeds while maintaining a comparable acoustic signature to submarines without auxiliary drives, improving handling characteristics and reducing the risk of acoustic detection.
Implementation Method 1
An inline thruster is an electrically powered propeller drive in which a stator is integrated into an annular housing. A hollow, annular rotor is rotatably mounted in the area of the housing where the stator is located, forming a water-permeable tunnel. Propeller blades are arranged on the inner circumference of the rotor
Implementation Method 2
This drive system thus involves the propeller being driven directly by a drive motor without the use of gears. This is advantageous in that it results in a comparatively high level of efficiency while producing a very low acoustic signature for the auxiliary drive
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The submarine has a pressure body (2) at least partially shrouded by an outer skin (4). The submarine has a main propeller drive and an auxiliary drive as an in-line thruster (22). The auxiliary drive can be moved from a rest position in the space (6) between the pressure body and the outer skin for deployment into the active position outside the skin at the under side of the submarine. The auxiliary drive is on a swing frame (8) and is coupled to a hydraulic or electric rotary drive (18). The auxiliary drive has a cladding (44), forming part of the outer skin.