Hydrodynamic performance of coaxial contra-rotating propeller (CCRP) for large ships

Hassan Ghassemi

doi:10.2478/v10012-008-0006-8

Abstract

Hydrodynamic performance of coaxial contra-rotating propeller (CCRP) for large ships This paper describes a coaxial contra-rotating propeller (CCRP) system to calculate the hydrodynamic characteristics and then obtain the optimum operational condition to install on two different large bulk carrier and VLCC. The method is based on boundary element method (BEM) to obtain the hydrodynamic performance of any complicated configuration such as CRP system, and then the optimum propeller data is obtained by the systematical method at the design condition. We prepared a software package code, namely SPD (Ship Propeller Design), which has model mesh generation, solver and numerical output results. The comparison of the propulsive performance was made between the propeller alone and CRP arrangement. Major finding include good agreement between predictions using the numerical code and experimental data for both ships.

Highlights

The main aims of the marine propulsor designers are to increase thrust, diminish torque, improve efficiency and to save energy
Most conventional propulsors are working behind the ship hull where the flow is non-uniform, unsteady and limitation of the propeller diameter due to ship stern
Single propeller produces cavitation at the heavy load condition, but coaxial contra-rotating propeller (CCRP) may provide moderate load on each blade and prevent cavitation. Another case is that the single propeller generates torque, while CCRP cancel the torque and improve the efficiency [1, 2]

Summary

INTRODUCTION

The main aims of the marine propulsor designers are to increase thrust, diminish torque, improve efficiency and to save energy. Single propeller produces cavitation at the heavy load condition, but CCRP may provide moderate load on each blade and prevent cavitation. Another case is that the single propeller generates torque, while CCRP cancel the torque and improve the efficiency [1, 2]. Rutundi [3] made a comparison test between CRP and conventional propeller for a 3500 tons naval training ship and has reported an 18% improvement in the propulsive performance. More attention is being drawn to the development of the contra-rotating podded propulsor (CRPP) system for ship propulsion because of its attractively high energy saving rate as well as lower cavitation and better hydrodynamic performance. Systematic design is employed to the two ships types (Bulk carrier and VLCC) to obtain the design points

Procedure of CCRP designing

NUMERICAL RESULTS AND DISCUSSION

CONCLUSIONS