Marine Propeller Support Member Cooling and Load Segmentation
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Solution Overview
Problem
Large marine propellers operating at low rotational speeds experience significant torsional stress, leading to bearing fatigue and reduced shaft life, with existing propeller arrangements often resulting in complex designs and overheating issues.
Innovation Solution
A propeller arrangement with a support member positioned outside the torsional domain, utilizing a single fluid for both lubrication and cooling, and a two-stage cooling system, along with a hydraulic fluid distribution unit positioned outside the torsional domain to minimize stress and facilitate efficient cooling and lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If large propellers operate at low rotational speeds, then fuel efficiency is improved, but bearing fatigue damage and shaft element fatigue life reduction occur
Solution Approach 1:
A support member is introduced as an intermediary element between the propeller shaft assembly and the hull. This support member carries a bearing arrangement that supports the shaft assembly, effectively distributing the load and reducing the stress on the main propeller shaft and its bearings, thereby extending their fatigue life while enabling low-speed operation
Solution Approach 2:
The propeller support system is segmented into multiple independent bearing arrangements: one bearing arrangement supported by the hull and another bearing arrangement supported by the support member. This segmentation allows each bearing to handle specific portions of the load, reducing the overall stress on individual components
2Strength
If bearings support the weight of large propeller shaft assemblies, then the propeller can be supported, but bearing overheating and burning occur
Solution Approach 1:
A cooling fluid conduit system is introduced as an intermediary thermal management pathway. The conduit is integrated into the support member and carries cooling fluid to the bearing arrangement, providing active cooling to prevent overheating while the bearing supports the full load
Solution Approach 2:
A hydraulic cooling system is implemented where cooling fluid is pumped through conduits in the support member to the bearing arrangement. This hydraulic system efficiently removes heat from the bearing, preventing overheating and burning while maintaining full load-bearing capacity
3Reliability
If propeller shaft assemblies are designed to cope with torsional stress, then reliability is improved, but device complexity increases
Solution Approach 1:
The support member and its bearing arrangement extract and carry a portion of the shaft assembly weight and support functions. This extraction reduces the complexity requirements of the main propeller shaft assembly, as it no longer needs to be over-engineered to handle all loads independently
Solution Approach 2:
The support function is segmented between the hull-supported bearing arrangement and the support member-supported bearing arrangement. This segmentation allows each component to be simpler and more specialized, rather than requiring one complex component to handle all functions
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
This design reduces the risk of bearing overheating and extends the life of bearings by maintaining lubricant viscosity, allowing for lower operational speeds and simpler, cost-efficient construction of propeller systems.
Implementation Method 1
Thanks to the possibility to cool down the first cooling fluid by means of circulating it within the support member, the first cooling fluid itself is cooled in an efficient way, and can also cool the bearing arrangement efficiently
Implementation Method 2
the first cooling fluid to lubricate the bearing arrangement, so as to allow the first cooling fluid to lubricate the bearing arrangement. The use of one single fluid as booth lubricant and cooling fluid for the bearing results in a simplified arrangement
Implementation Method 3
the bearing arrangement has a housing comprising at least one channel for guiding a second cooling fluid through the bearing housing. Thereby, a second cooling system for the bearing is achieved such that the bearing is cooled in a two-stage manner
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A propeller arrangement (100) for a marine vessel, the propeller arrangement (100) comprising a propeller (110), a propeller shaft assembly (120) comprising a shaft portion (122) extending from a distal side of the propeller (111 ), a support member (130) arranged to be connected to a hull (2) of the marine vessel, and a bearing arrangement (140) interconnecting the support member (130) and the shaft portion (122). The propeller arrangement is characterized in that the support member (130) comprises at least one cooling fluid conduit (131 ) for accommodating and circulating a first cooling fluid within the support member (130) and further to the shaft portion (122) and/or to the bearing arrangement (140).