Marine CU1 CU3 Propeller Bow Side Tunnel Thruster

Propeller Nickel Aluminum Bronze CU1 CU3 With 4 Blades 1700mm Diameter Marine Ship Vessel

Specification

Classification

Propellers are divided into two categories: fixed (propeller) pitch and variable pitch propellers.

Fixed pitch propeller

Wooden propellers are generally fixed pitch. Its pitch (or blade installation angle) is fixed.

The blade installation angle suitable for low speed is too small when flying at high speed; similarly, the installation angle suitable for high speed flying is too large at low speed. Therefore, the fixed-pitch propeller is more efficient only in the selected speed range, and is less efficient in other conditions. The fixed-pitch propeller has simple structure and light weight, and is widely used in light aircraft and ultralight aircraft with low power.

Variable pitch propeller

In order to solve the contradiction between the high and low speed performance of the fixed pitch propeller, a variable pitch propeller in flight appeared. The propeller pitch changing mechanism is driven by hydraulic or electric power. The first two-pitch propeller was used. Use high pitch at high speeds and low pitch at low speeds (such as take-off and climb conditions), and gradually increase the number of pitches to adapt to more flight conditions. The most complete variable pitch propeller is a constant speed propeller with a speed regulator. The speed regulator is actually a device that can automatically adjust the pitch and maintain a constant speed. The driver can change the speed of the engine and the propeller by controlling the regulator and the throttle. On the one hand, it can adjust the propeller's pulling force while keeping the propeller in the best working condition. On a multi-engine aircraft, when an engine fails and stops, the propeller rotates like a windmill under the action of oncoming airflow. On the one hand, it increases flight resistance and causes a large unbalanced torque. In addition, it may further damage the engine. For this reason, the variable pitch propeller can also automatically feather,

That is, the blades turn to the direction of the airflow to make the propeller stand still to reduce resistance. The variable-pitch propeller can also reduce the pitch and generate negative tension to increase drag and shorten the landing roll distance. This state is called reverse propeller.

In order to improve the economy of subsonic civil aircraft and reduce the fuel consumption of aircraft, the United States began to study a multi-blade propeller in the late 1970s, called a fan propeller. It has 8 to 10 scimitar-shaped blades with thin blades and small diameter. The shape of the scimitar can play the role of a swept-back wing (see swept-wing aircraft), and the thin blades are beneficial to increase the speed of the propeller. It is suitable for higher flying Mach number (M=0.8). Due to the large number of blades, the power absorbed by the propeller per unit propulsion area can be increased to 300 kilowatts/square meter (generally 80-120 kilowatts/square meter for propellers).

Picture

Docking inspection

(1) Drain the lubricating oil in the propeller hub and observe whether water enters the oil.

(2) The propeller shaft is also equipped with a sealing device, and its form is mostly Simplex type. Any cracks on the lip of the sealing ring, serious wear and aging, etc. should be replaced, and attention should be paid to the sealing performance.

(3) Check the fastening bolts and bolt anti-loosening devices of the blades and hubs.

(4) Check the sealing ring at the root of the blade (generally it should be replaced after 4 years).

(5) The propeller shaft bearings and drive shaft bearings are all rolling bearings. If they are found to be rusted, eroded, broken in the retainer, the rollers are severely worn or the rotation is not flexible, and the rotation is too loud, they should be replaced.

Effect

The side thruster is a special propulsion device that can generate lateral thrust (side thrust) of the ship. It is installed in the lateral guide tube below the waterline of the bow or stern, and the magnitude and direction of the thrust produced can be changed as required.

Generally, when a ship is berthing or leaving a wharf, crossing a canal, entering or exiting a sluice, or passing through a narrow waterway and crowded waters, one must drive slowly, and the other is to change its course frequently with a rudder. However, the slower the ship speed, the worse the rudder effect will be, which brings difficulties to ship maneuvering. Especially container ships, ro-ro ships, timber ships, etc. with a large wind-affected area, when navigating at low speeds, only relying on the rudder effect to change the course often cannot meet the requirements, so tugboats have to be used to help.

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