Environment-friendly propeller cavitation performance control technology

Technology overview: Identifying the cavitation performance of a real vessel propeller through a model propeller test is critical as it forms the basis of vessel propeller design and technology development. We have developed a three-dimensional ship wake flow reproduction technique and a model propeller cavitation performance test technique, which minimize the effect of Reynolds Number, generated due to difference in velocity of flow, and the relative sizes of a model vessel, used in the model test, and a real vessel.

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We have compared and verified the results of the model test with the results of the real vessel propeller real sea trial run, and found it shows excellence in the generation of a real vessel propeller cavitation, and the expected level of variable pressure and propeller noise. Such foundation technologies apply to mostly commercial vessels, including container ship, LNG carrier,  LPG carrier,  VLCC, and PC. We have gathered credible data on various vessel types. We have secured a technology capable of estimating a vessel body’s effective velocity, which uses the numerical analysis of organic speed generated by a propeller, and the results of total velocity measurement of a propeller, in a large cavitation tunnel. We have developed a numerical analysis technique that helps optimize the load distribution of a propeller and minimize cavitation generation, seeking for improving the efficiency of controlling and propelling a propeller cavitation, based on the aforementioned test techniques. We also have developed a technology for verifying the torque balance of a counter rotating propeller (CRP), a technology for improving propulsion efficiency using a Hub Vortex Control Fin, a technology for reducing the cavitation of a propeller blade and controlling the wake flow of a ship body, which makes use of a Vortex Generator, and a technology for reducing and stabilizing cavitations on a Rudder’s tip and shoe.

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Industrialization: The method of testing a large cavitation tunnel, developed in this project will apply to a model test for propulsor and will be used in the cavitation performance verification of a propeller designed in the basic design stage before constructing a vessel, followed by suggesting the direction of design improvement, based on the results. For example, for a 8800TEU container ship, we designed it having the optimal ratio of the expanded area ratio reduced by 15~20% based on the credible results of the model test, resulting in propelling efficiency improved by about 3~4%, and we were successful in commercialization. Moreover, the numerical analysis technology for optimizing propeller design has been transferred to the participating companies and being in use in designing propellers for export vessels. Currently, the research results of this project are utilized not only in the verification of commercial vessels’ propeller cavitation performance, built by domestic shipbuilders and technology development, but also in the national R&D research projert.

Problem-solving in industrialization: Cavitation, generated in a vessel’s propeller, gives various harms, including reduced propelling force and efficiency of a vessel, generation of variable pressure triggering vibrations in the vessel body, eroded surfaces of propellers and rudders, and radiated noise under the water. As such phenomena are not still fully numerically analyzed around the world, we are applying experimental methods at the same time to verify the technology. When we needed to submit precise test results, we had no option but to use foreign test facilities because we were lack in a large cavitation tunnel. Now, we have domestically secured the related test facilities, performance tests and designing methods, as aforementioned, it is now possible to conduct a credible verification in Korea. The technologies will contribute to improving domestic shipbuilding industry’s competitiveness in receiving orders due to the technological superiority, and will give a foundation to independent technology development.

Technology developer: Korea Research Institute of Ships and Ocean Engineering (KRISO) / +82-42-866-3114 / www.kriso.re.kr

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