Energy
A. Amini; N. M. Nouri; S. Niazi; A. Abedi
Abstract
Surface-piercing propellers (SPP) are known as one of the most efficient propellers in marine sciences and maritime industries. In this study, different types of simulations were performed on an SPP in various rotational speeds in open water conditions, and a numerical study was also carried out on a ...
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Surface-piercing propellers (SPP) are known as one of the most efficient propellers in marine sciences and maritime industries. In this study, different types of simulations were performed on an SPP in various rotational speeds in open water conditions, and a numerical study was also carried out on a particular type of such propellers. In fact the main purpose of this paper is comparing the simulation results with the experimental results from past in order to derive a trustable soultion for future works. For this purpose, the surface-piercing propeller was simulated by OpenFoam software (an open source software with high range of capabilities) in order to analyze the results. The performance curve was then plotted and compared with the ones from open water tests. In this case the turbulance model of K-Epsilon RNG was used which is capable of increasing Y+ to 300 which is monitored at the end of the simulation with the maximum amount of 315 and the average of 80. Results showed that the curves followed the same pattern and trends in the numerical study, and the report pointed to similar findings. In conclusion, it was proved that the sliding mesh method was a proper way for simulating propellers, particularly SPPs. The curves for thrust and torque coefficients of the SPP were also compared with the literature and the efficiency curve was plotted.
Energy
A. Amini; N. M. Nouri
Abstract
The Surface-Piercing propeller blades move in and out of the water with each rotation to reduce the immersion depth from the free surface to the shaft axis . The main challenge facing surface piercing propellers, however, is their lower efficiency at lower advance velocity, compared to other propulsion ...
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The Surface-Piercing propeller blades move in and out of the water with each rotation to reduce the immersion depth from the free surface to the shaft axis . The main challenge facing surface piercing propellers, however, is their lower efficiency at lower advance velocity, compared to other propulsion systems. To improve the performance of the propeller, an aeration mechanism was used at low advance velocities so that air was blown to the surface behind the propeller. Experimental studies were carried out on a propeller model in the Hydrotech laboratory of the Iran University of Science and Technology, and the effect of the injected air velocity ratio was evaluated at different immersion ratios. Based on the results obtained, it was concluded that an increase in the injected air velocity ratio could only promote thrust enhancement under specific conditions. For immersion ratios of 0.85 and more, as well as advance coefficients of 0.6 and more, a change in the velocity ratio of the injected air could not lead to an improvement in thrust. The best performance was identified with an immersion ratio of 0.4 and an advance coefficient of 0.4, while thrust performance at below or above of this condition declined .