Hongfei Cao^1,2, Zhongda Lyu^1,2,3,*, Xi Peng^2,3, Zhuo Zhao^2,3

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.9, pp. 2361-2384, 2023, DOI:10.32604/fdmp.2023.027470

Abstract In recent years, Remotely Operated Vehicles (ROVs) have played an increasingly important role in the construction and monitoring of underwater pile foundations. However, due to the open frame structure of such vehicles, a gap of knowledge still exists with regard to their hydrodynamic behavior. In this study, the hydrodynamic stability of such vehicles is investigated numerically by means of a multiple reference frame method. The hydrodynamic characteristics of the ROV when it moves horizontally and upward in the vertical plane are examined. It is found that there is interference between the horizontal and vertical thrusters of the ROV. There is… More >

Sikander Hans¹, Smarajit Ghosh¹, Suman Bhullar¹, Aman Kataria², Vinod Karar^2,*, Divya Agrawal²

CMC-Computers, Materials & Continua, Vol.71, No.3, pp. 6183-6200, 2022, DOI:10.32604/cmc.2022.020768

Abstract Today, ship development has concentrated on electrifying ships in commercial and military applications to improve efficiency, support high-power missile systems and reduce emissions. However, the electric propulsion of the shipboard system experiences torque fluctuation, thrust, and power due to the rotation of the propeller shaft and the motion of waves. In order to meet these challenges, a new solution is needed. This paper explores hybrid energy management systems using the battery and ultracapacitor to control and optimize the electric propulsion system. The battery type and ultracapacitor are ZEBRA and MAXWELL, respectively. The 3-, 4-and 5-blade propellers are considered to produce… More >

Jui-Hsiang Kao^*, Yi-Fan Liao

CMES-Computer Modeling in Engineering & Sciences, Vol.130, No.3, pp. 1325-1348, 2022, DOI:10.32604/cmes.2022.016212

Abstract This paper focuses on the ducted propulsion with the accelerating nozzle, and discusses the influence of its fluid acceleration quality on its propulsive performances, including the hull efficiency, the relative rotative efficiency, the effective wake, and the thrust deduction factor. An actual ducted propulsion system is used as an example for computational analysis. The computational conditions are divided into four combinations, which are provided with different propeller pitches, cambers, and duct lengths. The method applied in this study is the Computational Fluid Dynamics (CFD) technology, and the contents of the calculation include the hull's viscous resistance, the wave-making resistance, the… More >

Jun Huang^1,2, Chaopu Zhang¹, Song Xiang², Liu Yang¹, Mingxu Yi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.108, No.5, pp. 315-330, 2015, DOI:10.3970/cmes.2015.108.315

Abstract In order to accurately predict the aerodynamic noise of the propeller, a hybrid method combining Computational Fluid Dynamics (CFD) method with Boundary Element Method (BEM) is developed in this paper. The calculation includes two steps: firstly, the unsteady viscous flow around the propeller is calculated using the CFD method to acquire the noise source information; secondly, the radiated sound pressure is calculated using BEM method in the frequency domain. In comparison with the experimental results from wind tunnel, the calculated results of aerodynamic performance are rather desirable. The simulation and experimental results of aerodynamic noise are well fitted. The directivity… More >

F. Simonetti¹, R. M. Ardito Marretta²

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 81-90, 2000, DOI:10.3970/cmes.2000.001.383

Abstract Advanced propellers are being developed to improve the performance and fuel economy of future transport aircraft. To study them, various aerodynamic prediction models and systems (from theory to experiment) have been developed via several approaches (Free Wake Analysis, helicoidal source methods, scale model tests). This study focuses on the development of an efficient numerical method to predict the behaviour of rotor or propeller in forward flight. Based on a variational approach, the present numerical technique allows a significant reduction of computer resources used in the calculation of instantaneous velocities to determine the wake geometry and the three-dimensional vortex flow streaming… More >