Document Type : marine engineering


Department of Naval Architecture, Faculty of Marine Science and Technology, Science and Research branch, Islamic Azad University, Tehran, Iran


Many existing phenomena in nature are considered new design ideas in various fields of industry. Bionics is the application of biological methods and systems found in nature to the study and design of engineering systems and modern technology. By performing bionic review, the researchers found the penguins by delivering air locked under their wings and creating air bubbles, the drag significantly reduces. This motivates to study this factor in the marine industry by researchers and scientists. The overall drag of a marine vessel is directly proportional to the frictional drag. The reduction of frictional drag can be achieved by creating an air layer between vessel`s hull and flow around it. Creation of a cavity and cross channel of air can be easily just in order to reduce hull drag, while the air from a hole is injecting, the drag reduction up to 20 percent might be achieved. Experiments indicate that the pattern of wave drag reduces due to the air using and changes in pressure fields. In this research, by the use of theoretical relationships and the results of experiments, frictional drag reduction with different methods of air injection was investigated and then by the use of numerical software simulation (ANSYS-fluid flow), air injection on the floating model. The achieved results for drag reduction with decrease of wetted surface area at speeds of 4, 6 and 8 m/s are presented. By comparing the results of experiments(Harley high speed craft model) with software analysis and software simulation was validated. Due to high cost of manufacturing a model with air injection accessories and towing tank tests, with the acceptable precision results of this research, numerical software simulation (ANSYS-Fluid Flow) is more quick and efficient.


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