Propellers

Propellers

A propeller is a type of fan that transmits power by converting rotational motion into thrust.

Propelling Machineries:

The propeller, whatever its type, needs an engine to provide it with the necessary power for rotation, the propelling machinery may be one of the following:

1. Steam Engines.

2. Internal combustion or Diesel engines, (constant torque), this type of engines is divided into groups according to the speed of the engine as follows:

   a. Slow speed engines.

   b. Medium speed and high speed engines.

3. Marine Turbines.

Types of propellers:

1 - Arrangements concerning the number of propellers :

        a)   Single screw.

        b) Twin screw or multiple screws.

2 - Arrangements concerning the pitch of propeller blades:

        a)  Fixed pitch or conventional propeller.

        b) Controllable pitch propeller.

3 - Arrangements concerning special ideas for improving efficiency:

        a)  Nozzle propellers ( decelerating , accelerating )

        b) Tandem propellers and contrarotating propellers.

        c)  Overlapping propellers.

Materials of propellers

a. Cast Iron

b. Cast Steel

c. Manganese Bronze

d. Manganese - Nickel - Aluminum Alloys

e. Bronze - Brass alloys