Seyyed Mostafa Seyyedi, Rouzbeh Shafaghat, Negin Donyavizadeh,
Volume 10, Issue 0 (7-2018)
Abstract
Surface-piercing propellers have been widely used in light and high-speed vessels because of their superior performance. One of the major steps in propeller selection algorithm is the determination of thrust as well as torque hydrodynamic coefficients. For the purpose of simplifying design and selection procedure, some relations are presented for determining hydrodynamic coefficients in some studies, precision, and accuracy of which must be validated due to the importance of the issue as well as having high development and operational costs. Therefore, these issues are evaluated in this study by field study and recognizing the presented relation set as well as acquiring experimental test data. The acquired results show lack of full agreement between semi-experimental relations and experimental data. In the following, due to the limitations of the regression relations presented in the determination of hydrodynamic coefficients, the database was developed from experimental data, the number of series is determined by extracting the regression relations for each series, these relations are used to determine the hydrodynamic coefficient of thrust and torque in the propeller selection algorithm. Finally, a suitable algorithm for selecting the surface-piercing propeller was presented and discussed
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Ehsan Asadi Asrami, Mohammad Moonesun,
Volume 18, Issue 0 (5-2023)
Abstract
To obtain the hydrodynamic forces acting on a solar-powered AUV, and to investigate the effects of the free surface, a model of this type of vessel was simulated in ANSYS FLUENT 18 commercial software. To validate the data, a vessel with a scale of 1: 1 compatible with the installation of photovoltaic panels was built and tested in the towing tank of the National Iranian Marine Laboratory (NIMALA). The standard k-ε model and multi-block mesh were used to simulate the three-dimensional unsteady viscous flow around these cases: individual struts, the body without struts, and the body with struts. Three depth-to-diameter ratios ( h d =3.6 , 4.5 , 5.2 ) and six Froude numbers in the range of 0.06 ~ 0.35, equivalent to the Reynolds range 2.4×10 05 to 1.4× 10 06 , were used to obtain lift and drag coefficients. The findings of this study were used to create a solar AUV. The maximum percentage of struts contribution in the total resistance force is 62 percent. The generated resistance effect, caused by struts and their attachment to the body, also plays a significant role. According to the current study data for the analyzed model, its maximum value is around 41 percent.
