International Journal of

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Surface-Piercing Propellers (SPPs) have been widely used in high speed craft due to some desirable features such as high efficiency, omission of resistance of equipment attached to the propeller and proper functioning of cavitation. Unlike the submerged propellers, theoretical methods have no significant application on simulation of SPPsbecause of problems related to modeling of these propellers. Design of SPPs is mainly done based on empirical studies and model experiments. Water tunnel or free surface cavitation tunnel is among the most important devices to perform SPPs model testing. In this paper, the design algorithm of a free surface water tunnel to test the SPPs has been described. The design and construction stages of the free surface cavitation tunnel of Babol Noshirvani University of Technology are provided. Also,calculation of its various sectors such as elbows, nozzle, settling chamber, test section, diffuser and calculation of pressure drops, proper pump selection and dynamometer  has been showed.

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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.