Propeller Assembly Gas Gap Friction Reduction
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Solution Overview
Problem
Existing ship propeller and generator assemblies experience significant energy loss due to friction forces in gaps between rotating and stationary sections when submerged in water, with losses increasing with peripheral velocity and medium density.
Innovation Solution
The assembly replaces the liquid in these gaps with a gas, such as air, to reduce friction losses, utilizing gas channels and overpressure to ensure gas displacement of water, thereby reducing frictional resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the propeller assembly operates in water, then propulsion function is achieved, but friction losses in gaps increase significantly
Solution Approach 1:
The patent introduces gas (air) as an intermediary substance in the gaps between rotating and stationary sections. This gas layer acts as a mediator that reduces direct contact friction between water and rotating components, thereby reducing energy losses while maintaining propulsion function.
Solution Approach 2:
The patent applies pneumatic principles by introducing gas into the gaps between rotating and stationary sections. This creates a gas-filled environment that reduces frictional resistance compared to liquid-filled gaps, improving overall system efficiency.
2Speed
If peripheral velocity increases, then propulsion efficiency improves, but friction losses increase with the third power of velocity
Solution Approach 1:
The gas layer serves as a velocity-independent intermediary that reduces friction losses regardless of the rotational speed. By maintaining a gas-filled gap, the system reduces the cubic velocity dependence of friction losses.
3Reliability
If the gap between rotating and stationary sections is reduced, then mechanical coupling improves, but friction losses in the gap increase
Solution Approach 1:
The gas layer acts as a mediator that allows for reduced gap dimensions while maintaining reliable mechanical coupling. The gas-filled environment reduces friction losses in the smaller gap, enabling better coupling without the penalty of increased friction.
4Temperature
If water is present in gaps, then cooling effect is provided, but friction losses increase due to high density
Solution Approach 1:
The gas layer serves as an intermediary that reduces friction losses by a factor of 800 compared to water. While the cooling effect is reduced, the dramatic reduction in friction losses provides net energy efficiency improvement.
Solution Approach 2:
The patent changes the physical parameter of the gap medium from liquid (water) to gas (air). This parameter change fundamentally alters the density and friction characteristics, reducing friction losses by a factor of 800 despite the trade-off in cooling effectiveness.
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 approach significantly reduces friction losses by approximately 30% of the total delivered power, achieving substantial energy efficiency improvements by lowering frictional resistance by a factor of 800 due to the lower density of gas compared to water.
Implementation Method 1
gas channels (33) in the stator part (23), for delivery of gas, preferably air, to the gap (31). The gas can be delivered by means of application of overpressure in the gas channels (33)
Implementation Method 2
When the rotable sections are rotated, friction forces arise in the medium in the gaps. This results in energy loss... the losses are linearly dependent on the density of the medium in the gap, as a higher density results in higher losses
Data Source
Figure 1~2
Figure 3~4
AI summary
Assembly for use as a ship propeller (11) or a turbine in a current of water, comprising a propeller section (15) with at least one propeller blade (15a), a rotor part (25) arranged about and co-rotating with the propeller section (15), which rotor part (25) in its periphery comprises magnet devices (27) or windings for the generation of magnetic fields, so that the rotor part (25) constitutes the rotor of an electric motor and/or generator. The assembly further comprises a stator part (23) that surrounds the rotor part (25), which stator part (23) comprises magnet devices or windings (29) for generation of magnetic fields. The assembly is adapted for the supply of gas in at least one gap (31) between the rotor part (25) and the stator part (23), for displacement of any liquid in the gap (31) for the reduction of frictional forces in the gap (31) during rotation of the rotor part (25) in relation to the stator part (23).