Method of controlling rotational speed of propeller of ship to reduce cavitation

A method for controlling a rotational speed of a propeller of a ship to reduce cavitation, the method comprising:

• generating cavitation information about the cavitation occurring during rotation of the propeller;
• measuring a rotational angle of the propeller in real time after generating the cavitation information;
• and
• changing a rotational speed of the propeller using the generated cavitation information and the measured rotational angle of the propeller such that an occurrence of the cavitation is reduced,
• wherein the cavitation information comprises information about a rotational angle of the propeller at a time of the occurrence of the cavitation,
• wherein the generating of the cavitation information comprises:
• measuring fluctuating pressure applied to a stern of the ship in water, the fluctuating pressure being caused by the cavitation occurring on surfaces of blades of the propeller during the rotation of the propeller;
• measuring the rotational angle of the propeller to generate the cavitation information;
• and
• generating the cavitation information by using the measured fluctuating pressure applied to the stern of the ship and the measured rotational angle of the propeller,
• wherein the generating of the cavitation information further comprises:
• time-synchronizing information about a first fluctuating pressure applied to the stern of the ship in water near a descending propeller blade with information about the rotational angle of the propeller, the first fluctuating pressure being caused by the cavitation occurring on a surface of the descending propeller blade during the rotation of the propeller;
• generating first cavitation information about the cavitation occurring around the descending propeller blade using the time-synchronized information about the first fluctuating pressure and the measured rotational angle of the propeller;
• time-synchronizing information about a second fluctuating pressure applied to the stern of the ship in water near an ascending propeller blade with information about the rotational angle of the propeller, the second fluctuating pressure being caused by the cavitation occurring on a surface of the ascending propeller blade during rotation of the propeller;
• generating second cavitation information about the cavitation occurring around the ascending propeller blade using the time-synchronized information about the second fluctuating pressure and the measured rotational angle of the propeller;
• and
• generating the cavitation information including the first cavitation information and the second cavitation information.