Comparative study on hydrodynamic performance and induced pressure of new canard tandem propellers and conventional propellers

Abstract

Thrust, efficiency, induced pressure on hull surface and negative pressure distribution on blade surface of five conventional propellers and twenty-eight tandem propellers were studied comprehensively by numerical method to assess the ability of two different types of propellers in dealing with efficiency, cavitation, vibration and noise problems. The flow field was simulated by solving RANS equations with SST k-ω turbulence model. For the conventional propellers, the effect of disk ratio and number of blades was investigated. For the tandem propellers, the vortex-blade interaction and effect of blade phase angle and diameter ratio were studied. Then, a comparison was made between new tandem propellers and conventional propellers. Results show that, compared with the conventional propeller with larger disk ratio and more blades, the efficiency of the tandem propeller is much higher in most working conditions, the induced pressure is comparable and cavitation performance is a little bit worse; compared with the conventional propeller with smaller disk ratio and fewer blades, although the tandem propeller has relatively lower efficiency, the induced pressure is significantly reduced and cavitation is improved obviously. The study shows that the new tandem propeller has more advantages and potentials than the conventional propeller in dealing with these problems.