FORCES ON THE MANOEUVRING SHIP PROPELLER

The longitudinal and lateral components of hydrodynamic force on propeller of manoeuvring ship are considered in the paper. Data of the Shipbuilding manual (Sudostroenye, Leningrad,1973) are used to define the longitudinal force. The propeller thrust is shown as an universal coefficient versus universal propeller advance. That allows us to analyze the longitudinal force for all possible values of model speed and propeller frequency. The lateral component of hydrodynamic force is measured in circular towing tank. The propeller force is measured on the model shaft using the miniature dynamometer placing in deadwood pipe. While side force measuring, in addition to changing the model velocity and propeller rotation frequency, the drift angle is changed. Both components of hydrodynamic force on the propeller are shown as a diagram versus universal propeller advance. To calculate the universal propeller advance for longitudinal component of force the velocity projection on X-axis is used, and to calculate the universal propeller advance for lateral component of force the velocity projection on Y-axis is used. The universal coefficients represented in that way do not depend on the propeller work conditions, i.e. the independent parameters number is reduced. The universal lateral component of force turns up multiplevalue. The universal advance maximum and minimum values divide the curves into parts at points corresponding to 90° и 270° drift angles.