Anti-cavitation twisted rudder and design method thereof

Abstract

The invention belongs to the field of ship or rudder design and particularly relates to an anti-cavitation twisted rudder and a design method thereof. On the basis that the influence of various factors such as the rotational speed in the ship propeller wake flow on the rudder is fully considered, the geometrical attack angles and line types of all the spanwise position sections are designed and determined through the distribution characteristic of a propeller rear wake flow field in direct sailing of a ship, so that the geometrical shape of the rudder is matched with that of the propeller wake flow field, and the purposes that the pressure distribution of the rudder surface is improved, the cavitation starting sailing speed of the rudder is increased, the time of rudder cavitation is shortened, the area of rudder cavitation is decreased, vibration and noise caused by the rudder are reduced, cavitation denudation of the rudder surface is restrained, the maintenance cost of the rudder is saved, the force state of rudder blades is improved, the rudder efficiency is improved, and the load of the rudder is reduced are achieved.

Description

technical field [0001] The invention belongs to the field of ship or ship rudder design, in particular to an anti-cavitation twisted rudder and a design method thereof. Background technique [0002] In recent years, due to the development of high-speed and large-scale ships, especially for high-speed ships, the vibration and cavitation erosion of the rudder blades working behind the propellers are becoming more and more serious, so the consideration of rudder performance is becoming more and more comprehensive. . The left and right sides of the traditional rudder blade are in a symmetrical form with the center plane of the rudder. This shape feature does not take into account the impact of the strong rotating wake of the propeller on the rudder blade, which leads to serious cavitation in traditional rudder blades. Not only will it cause cavitation erosion on the surface of the rudder blade, but it will also lead to a substantial increase in vibration and noise. [0003] Du...

AI Technical Summary

Problems solved by technology

The reason is mainly because ordinary rudders do not take into account the characteristics of the propeller's rotating wake, which leads to serious cavitation in traditional rudders.

The cavitation of the rudder will cause serious erosion of the rudder surface, which will affect the service life of the rudder, and will also cause a significant increase in vibration and noise

[0005] Since the steering force of the rudder is formed by the pressure difference between the pressure surface and the suction surface of the rudder blade, when cavitation occurs on the suction surface, the pressure remains at the saturated steam pressure and cannot be further reduced, so the rudder effect will be obvious after cavitation occurs reduce

In addition, the cavitation of the rudder will also generate a lot of noise, causing a series of adverse effects such as vibration of the rudder and the tail structure

[0006] When the ship sails straight at a rudder angle of 0°, due to the rotation of the propeller wake, the pressure distribution on the left and right sides of the rudder blade is asymmetrical, and there will be a large lateral force and rudder shaft torque on the traditional rudder. The lateral forces of the left and right rudders cancel each other out, which does not affect the ship's direct sailing performance, but the existence of the torque of the rudder shaft will increase the load on the steering gear

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