Asymmetric wake generating vortex generator for reducing propeller noise and vibration

Abstract

The present invention relates to an asymmetric wake generating vortex generator for reducing propeller noise and vibration, configured such that, by controlling a flow that is introduced into a propeller installed on a ship so as to reduce cavitation that occurs on a wing surface of the propeller of the ship, the noise and vibration of the propeller can be reduced. Conventional wing-shaped added materials or flow control fins have the following problems: a wing-shaped structure is attached to the surface of a hull in front of a propeller and, in order to control a flow introduced into the propeller, is made to have an angle of attack with regard to the introduced flow; therefore, the same is configured to control the velocity of flow and the direction of flow, resulting from a fluid force, and thus can exhibit an effect only when the same is a large structure; furthermore, when the same is attached to the surface of the hull in front of the propeller so as to change the velocity in the tangential direction, the resulting pre-swirl effect improves the efficiency of the propeller, while the increased cavitation increases noise and vibration of the propeller. In order to resolve the above problems, the present invention provides an asymmetric wake generating vortex generator for reducing propeller noise and vibration, configured such that the angle of attack, which is introduced to a wing surface, is reduced through a change in velocity in the axial direction resulting from generation of an asymmetric vortex, thereby generating an asymmetric wake distribution that makes the flow on a first or second quadrant of a propeller surface, on which the largest degree of cavitation occurs, particularly fast, and thereby minimizing generation of cavitation noise.

Description

technical field [0001] The present invention relates to a device and method for reducing noise and vibration of a propeller mounted on a ship, and more particularly, the present invention relates to a method for generating an asymmetrical wake for reducing propeller noise and vibration A vortex generator that controls the flow into the propeller to reduce cavitation that occurs on the blade surface of the ship's propeller and thereby reduce the noise and vibration of the propeller. Background technique [0002] Ships generally move forward with a propeller, which is connected to the rotating shaft of the engine installed on the hull and rotates with the driving force of the engine to generate propulsion. The propeller is designed according to each operating condition. Blade shape and size. [0003] Also, the propeller generates thrust and torque by means of the flow through the propeller blades, at which point the driving force of the engine overcomes the torque and uses th...

AI Technical Summary

Problems solved by technology

[0012] Moreover, said wing-like appendages or flow control fins, without considering the reduction of propeller noise and vibration, also reveal a change in the direction of the horizontal (tangential) in the flow into the propeller to produce pre-swirl (Pre-swirl ) effect and thereby improve the efficiency of the propeller. Although these devices can improve the efficiency of the propeller, they will also increase the angle of attack on the blade surface and cause excessive cavitation on the propeller surface. In terms of propeller noise and vibration cause bad influence

[0013] The wing-like appendages or flow control fins of the prior art have the problem as mentioned above, that is, the surface of the hull placed in front of the propeller, in order to control the flow into the propeller, the wing-like structure has The angle of attack between the incoming flow and the fluid force controls the flow velocity and flow direction, so it can only be effective when it becomes a large structure, and although it can be controlled by changing the velocity in the horizontal (tangential) direction The flow flowing into the propeller and relying on the preswirl effect to improve the propeller efficiency will cause the side effect of increasing the noise and vibration of the propeller due to the increase of cavitation. Therefore, in order to solve the above problems, preferably, the following should be provided A vortex generator with a new structure, which can generate a vortex that can control the flow rate even if it is a small structure, and depends less on the speed change in the horizontal direction and more on the speed change in the axial direction. Reduces the angle of attack of the inflow blade face, thereby increasing the flow velocity in general and forming the first quadrant side of the propeller face where cavitation occurs most when the propeller rotation direction is clockwise when viewed from the stern side towards the bow side The asymmetric wake distribution with particularly fast flow can minimize the occurrence of cavitation noise, but so far no device or method has been developed that can satisfy all the above conditions at the same time

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