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Numerical analysis of resistance characteristics of a novel high-speed quadramaran

Liu Xin, Yang Jinglei, Wu Defeng, Hou Liang, Li Xiaowen, Wan Qian

Polish Maritime Research

2023

nr 2

11--27

This paper utilised computational fluid dynamics (CFD) technology to calculate the resistance of a novel high-speed quadramaran in calm water using the Navier‒Stokes (N‒S) equation, analysed the total resistance, frictional resistance, and residual resistance characteristics of this novel high-speed quadramaran at different length Froude numbers, and compared them with the results of a conventional high-speed catamaran with the same displacement. The results showed that the total resistance of the quadramaran had a significant hump at the Froude number of 0.6, due to the complexity of the wave interference among the four demihulls, and the hump value was about 1.6 times that of the catamaran. Above the hump speed, the total resistance of the quadramaran decreased with the increase of the Froude number, until reaching the Froude number of 1.06, when the curve became flat, and it showed a maximum resistance reduction of 40% at the Froude number of 1.66 compared with the catamaran, where the total resistance curve was steep. The frictional resistance of the quadramaran increased gradually with the growth of the Froude number, which was basically consistent with the change trend of the catamaran. The residual resistance of the quadramaran first rose and then reduced with the rising Froude number, the curve showed a large hump due to the adverse wave interference, and the hump value was about 1.7 times that of the catamaran. Above the Froude number of 1.06, as the wave interference changed from adverse to favourable, the quadramaran had lower residual resistance than the catamaran. The bow and stern demihulls of the quadramaran were also analysed for their resistance characteristics. The total resistance of the bow demihulls increased gradually with the increase of the Froude number, the curve had a small hump at the Froude number of 0.7, and above the hump speed, the curve was steep. The total resistance of the stern demihulls first increased and then decreased with the growth of the Froude number, the hump value at the Froude number of 0.85 was significant and was about 2 times that of the bow demihulls, and the curve became flat above the Froude number of 1.51.

Flow field characteristic analysis of cushion system of partial air cushion support catamaran in regular waves

Yang Jinglei, Sun Han-bing, Li Xiao-wen, Liu Xin

Polish Maritime Research

2022

nr 3

21--32

In order to study the flow field characteristics of cushion system of partial air cushion support catamaran (PACSCAT) in waves, an analysis was carried out involving flexible treatment on the bow and stern air seals to simulate air seal shape under test conditions by means of computational fluid dynamics method and fluid structure interaction (FSI) method. On this basis, the pressure conditions of the air cushion chamber and the pressurized chamber at different wavelengths and different speeds are studied and compared with experimental results. The experimental results show that: for the air cushion pressure, the nonlinear characteristics of the numerical calculation results are more subtle than the experimental values, after linear transformation, the amplitudes of the experimental values are obviously greater than the calculated values after linear transformation, but the average values are not much different; At low speed of 2.0m/s, the spatial pressure distribution of the pressurized chamber and the air cushion chamber are uniformly distributed, at high speed of 3.6m/s, except for a certain pressure jump occurred in the air cushion chamber near the stern air seal, the pressure in other spaces is also evenly distributed, it proves that the pressurized chamber type of air intake can effectively meet the air cushion pressure balance.

Preparation of rGO/ZnO photoanodes and their DSSCs performance

Li Jiake, Wu Lanxiang, Li Wentao, Chen Ying, Liu Xin, Jiang Hedong, Guo Pingchun, Zhu Hua, Wang Yanxiang

Materials Science Poland

2022

Vol. 40, No. 2

170--180

In this study, we report a mild and controllable preparation method for graphene oxide (GO) and ZnO ultrafine powder, respectively. On this basis, reduced graphene oxide (rGO)/ZnO composite powder for the photoanodes of dye-sensitized solar cells (DSSCs) was synthesized by chemical reduction method. Phase composition, microstructure, chemical structure, conductivity, and specific surface area were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), Raman, and Brunauer-Emmett-Teller (BET) method, respectively. Photoelectric performance of DSSCs was studied by the current density-voltage (J-V), electrochemical impedance spectra (EIS) photoelectric test system. As rGO possesses higher adsorption capacity and excellent conductivity, hence it may effectively promote separation of electrons and holes, transmission ability of electrons and holes, and utilization of the light. By contrast, the as-synthesized zinc oxide (ZnO) may increase adsorption capacity of dye molecules, so photoelectric conversion efficiency (PCE) of the solar cells is increased by means of synergistic effects. When adding rGO in the rGO/ZnO composite powder at 1.25 wt%, PCE reaches to 6.27%, an increase of 20.6% more than that of pure ZnO as the photoanode.