Controllable pitch propeller actuating mechanism, modelling and simulation

Abstract

This article focuses on the mathematical model of the pitch control mechanism for a marine controllable pitch propeller, with the aim of describing the dynamic behaviour of this kind of system and its influence on ship performance. Too great a load on the blades can result in high pressures in the actuating system, response delays and control system problems, which are ultimately responsible for most mechanism failures. The behaviour of the controllable pitch propeller actuating mechanism is considered in terms of blade position, oil pressures inside the controllable pitch propeller hub and magnitudes of the forces acting on the blades. In the proposed mathematical model, the forces acting on the propeller blade are evaluated taking into account the yaw motion of the ship, the propeller speed (including shaft accelerations and decelerations) and the turning of the blade during the pitch change. On the basis of the introduced procedure, a controllable pitch propeller numerical model as part of an overall propulsion and manoeuvrability simulator representing the dynamic behaviour of a twin-screw fast vessel is developed. The aim of this work is to represent the ship propulsion dynamics through time-domain simulation, based on which the designers can develop and test several design options, in order to avoid possible machinery overloads with their consequent failures and to obtain the best possible ship performances. In this aspect, the controllable pitch propeller model is an essential design tool.

Torsional fretting and torsional sliding wear behaviors of CuNiAl against 42CrMo4 under dry condition

“…In the blade bearing, CuNiAl and 42CrMo4 are the common materials used for the hub and blade carrier respectively [3] ; [4]. In this study, CuNiAl was chosen as the material for the lower specimens, and 42CrMo4 was chosen as the material for the upper specimens.…”

“…1 shows the crosssection of a controllable pitch propeller (CPP), in which the blade carrier, the blade foot together with the hub form a blade bearing. Godjevac et al [3] ; [4] reveal that both torsional fretting and torsional sliding wear can happen on the inner radial part of the blade bearing. The fretting wear happens when the pitch is fixed, but due to the fluctuation of wake flow field and rotation of the CPP a maximum 500 μm fretting motion can happen within the clearances of the bearings.…”

Amerigo Vespucci: Retrofitting of propulsion and generation systems on the italian training's tall ship

“…A similar software has been realized for ship's propulsion dynamic performance prediction, demonstrating how powerful such approach can be [13]. Indeed, the analysis of the interactions that arise between sea, hull, propeller, and propulsion motor is rather complex and is nearly impossible to model without using numerical simulations [14][15][16].…”

Removal Notice: Simulation of dynamical loads for large controllable pitch propellers ground tests

“…When the pitch is sable, the CPP can be regarded as a fixed pitch propeller, and the hydrodynamic calculation method can be used. Propeller thrust P is calculated as follows [6][7][8]…”