Abstract

The proper evaluation of the Rudder–Propeller interactions is mandatory to correctly predict the manoeuvring capability of a modern ship, in particular considering the commonly adopted ship layout (rudder often works in the propeller slipstream). Modern Computational Fluid Dynamics (CFD) solvers can provide, not only the performance of the whole system but also an insight into the flow problem. In the present paper, an open-source viscous flow solver has been validated against available literature experimental measurements in different conditions. After an extensive analysis of the numerical influence of the mesh arrangement and the turbulent quantities on the rudder provided forces, the study focused its attention on the forces generated by the rudder varying the propeller loading conditions and the mutual position between the two devices. These analyses give a hint to describe and improve a commonly-used semi-empirical method based on the actuator disk theory. These analyses also demonstrate the ability of these numerical approaches to correctly predict the interaction behaviour in pre-stall conditions with quite reasonable computational requests (proper also for a design stage), giving additional information on the sectional forces distribution along the span-wise rudder direction, useful to further develop a new semi-empirical rudder model.

Highlights

  • The rudder is the most common steering device adopted to control the ship track

  • The traditional manoeuvrability methods based on semi-empirical mathematical models ([8,9,10]) require a correct hull forces description ([11,12]) and a complete and accurate model of rudder performance, able to provide their forces starting from kinematic quantities and known propeller settings

  • After the description of the used propeller model and an in-depth comparison with the actuator disk theory in Section 4, the open-water rudder performances are compared with available experimental measurements (Section 5) focusing attention on the influence on the simulation results caused by the mesh arrangement and the turbulent quantities

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Summary

Introduction

The rudder is the most common steering device adopted to control the ship track. It is a lifting surface positioned, normally, in the stern ship region which, generating a lateral force, guarantees to perturb the ship direction. After the description of the used propeller model and an in-depth comparison with the actuator disk theory, the open-water rudder performances are compared with available experimental measurements (Section 5) focusing attention on the influence on the simulation results caused by the mesh arrangement and the turbulent quantities. These preliminary results provide the basic model set-up for the successive numerical and experimental comparisons when the rudder operates behind the propeller in different reciprocal positions (Section 6).

Numerical Background
Test Cases
Analysis of the Effectiveness of the Propeller Approach
Open-Water Rudder Analysis
Rudder behind Propeller
Propeller Load Effect
Propeller Position Effect
Rudder–Propeller Model
Rudder Sectional Force Analysis
Findings
Conclusions
Full Text
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