Pre-swirl Generator Wedge Angle for Marine Propulsion Efficiency
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Solution Overview
Problem
Existing marine vehicles face inefficiencies in propulsive force due to turbulence and dissipation losses from propellers, and existing solutions like flow guiding shrouds increase resistance and cost, while attempts to reduce vibration consume additional horsepower.
Innovation Solution
A marine vehicle equipped with a pre-swirl generator featuring a swirl creating wedge mounted on the hull, inclined at an angle of 13°-45°, which generates a pre-swirl flow to improve propulsive efficiency by reducing the required propulsive power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a flow guiding shroud is provided around the propeller to gather and convert dissipation energy into propulsive energy, then propulsive efficiency is improved, but resistance to propeller rotation increases and cost increases
Solution Approach 1:
The invention divides the flow control function into two parts: the pre-swirl generator (separate wedge-shaped device) handles the swirl generation, while the propeller handles propulsion. This segmentation avoids the need for a comprehensive flow guiding shroud that would increase resistance, allowing independent optimization of each component's function.
Solution Approach 2:
The pre-swirl generator acts as an intermediary device between the hull and the propeller. It modifies the incoming flow by generating pre-swirl before the fluid reaches the propeller, thereby improving propulsive efficiency without the propeller being directly subjected to the resistance-inducing shroud structure.
2Power
If the rotational speed of the propeller is increased to improve propulsion, then propulsive force increases, but turbulence and dissipation loss increase
Solution Approach 1:
The pre-swirl generator performs preliminary action by creating pre-swirl flow conditions before the fluid reaches the propeller. This pre-conditioning of the flow reduces turbulence and dissipation losses during propeller operation, allowing for more efficient power conversion without excessive energy loss.
3Object-affected harmful factors
If triangular hydrofoils are fitted on port and starboard quarters to reduce vibration, then vibration is reduced, but additional propulsive horsepower is consumed
Solution Approach 1:
The invention extracts the vibration reduction function from the complex triangular hydrofoil system and implements it through the pre-swirl generator's simplified wedge structure. By taking out only the essential swirl-generating capability, the system achieves vibration reduction without the excessive horsepower consumption associated with full hydrofoil assemblies.
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 pre-swirl generator reduces the needed propulsive horsepower by 0.27-0.37% and enhances propulsive efficiency, as demonstrated through computational fluid dynamics simulations on a 1,700 TEU container vehicle, with potential for further reduction in power loss.
Implementation Method 1
a pre-swirl generator having a swirl creating wedge disposed in the swirl generator mounting region and inclined with respect to the waterline by an angle of 13°-45°
Data Source
AI summary
A marine vehicle includes a hull, a rudder, a propeller, a swirl generator mounting region provided on an outer surface of the hull and located on a port side or a starboard side where a rotation direction of the propeller is downward, and a pre-swirl generator having a swirl creating wedge disposed in the swirl generator mounting region. The swirl generator mounting region is disposed in front of a central axis of the rudder and behind a vertical line spaced from the central axis by a distance that is 0.2 times the length of the vehicle. The swirl creating wedge is inclined with respect to a waterline by an angle (θ1) of 13°-45°. The pre-swirl generator can produce a flow guiding effect that enhances propulsive efficiency of the marine vehicle.