Propeller Cap Turbine 1k496a

Propeller Cap Turbine (PCT) Because of its almost uniform effectiveness in both full-load and ballasted conditions, the propeller cap turbine (PCT) is generally the most cost-beneficial of the listed SAHESD’s. It is easily designed for retro-fit and the relatively low cost can be recovered quickly. (See Reference 3.) By installing a properly designed PCT, with varying pitch of air-foiled shaped blades integrally cast into the hub cap, energy from the rotating fluid coming off the propeller hub is recovered by these small shaped blades, and hence energy savings is achieved over a wide-operating range of ship speed and draft/trim conditions. A device similar to the PCT, but proven to be less-efficient and more-expensive in competition, is called the PBCF (Propeller Boss Cap Fin) which utilizes only flat plates. It has been installed on more than 600 ships in Japan with some ships having installed power over 40,000 horsepower and in sizes above 140,000 tons deadweight. (See Reference 4.) To properly design an efficient PCT, technical information is needed about the ship as listed under Engineering Input. Because open-water propeller tests should be conducted to design the PCT, time to manufacture the PCT is about 5 months. Sea shipment from Shanghai to any location worldwide can be done in less than 6 weeks. In addition, air freight can be arranged as an alternative to sea transport in urgent delivery situations. Large units for 40,000 to 60,000 HP propellers weigh in the region of 2500kg and are somewhat less than one-third of the propeller diameter, or about 2.500 meters. Because weight of the PCT represents only about 1 to 2% of the propeller weight and propeller torque is reduced about 3 to 5%, there appears to be only a very small influence of the PCT on engine RPM and shaft torsional vibration. However, for a reasonable fee, calculations can be provided, but has not been required by classification society in previous applications, to quantify the expected influence. Also note this torque reduction can provide a benefit to diesel propulsion engines that are operating in a heavily loaded condition. Significant cost-benefit can be gained from application of the PCT to propellers on all type of ships: tankers, bulk carriers, and container ships. Even ships with controllable-pitch propellers have been fitted with PCT’s.

Equally efficient and cost effective, both in installation and operation, are devices that can be placed to the aft of the propeller. Two of these devices, the Propeller Boss Cap Fin (PBCF) and Propeller Cap Turbine (PCT), can be added to the propeller’s rear in place of the normal boss cap; both perform the identical function of recapturing some of the rotational energy generated by the propeller.

Propeller Boss Cap Fins

Without the need to send a fleet to scrap and invest in new eco-design ships feeling their way on to the market, proven propeller appendages, both mature and new, are currently available to help drive costs down and improve the long-term outlook for owners and operators. The devices mentioned in the article are by no means an exhaustive list of the propulsion enhancers available on the market. For further information on other propeller modifications, appendages, rudder devices and a whole host of fuel-saving technologies and products, hip of Fathom-CTech is available at a monthly rate.

Abstract Computational fluid dynamics (CFD) analyses of propeller boss cap fins (PBCF) were carried out for two different propellers at model and full scale Reynolds numbers with two different inflow conditions. Computations corresponding to the reverse propeller open test (POT) experiment were confirmed to be in a good agreement with the measurement. The results of computations at different conditions have shown that increased Reynolds number and presence of hull wake both positively influence the effects of PBCF. Due to the combined effect of the Reynolds number and the wake, the gain in the propeller efficiency at the full scale condition was found to be significantly larger than that at the model test condition. The detailed investigation of the results suggested that the fin drag becomes smaller and the reduction of the boss drag becomes larger at the full scale condition. However, the predicted gain is still smaller than the values reported in the sea trial and logbook analysis. The remaining gap may be attributed to the difference in the estimated and actual wake distribution or to other factors such as interactions with hull and rudder, surface roughness, unsteadiness and hub vortex cavitation.

Tokyo, Japan: Mitsui OSK Techno-Trade has announced the application for an additional patent on the propeller boss cap fins (PBCF) system, tly developed by MOTech, Akishima Laboratries (Mitsui Zosen), and Mitsui OSK Lines.

The new patent covers innovations that make the PBCF more effective in saving fuel and protecting the environment. The PBCF is an energy-saving system for propeller-driven ships, and has been adopted on 1,700 vessels around the world. It is installed at the rear of the propeller, breaking up the hub vortex formed behind the rotating prop. It reduces the torque of the propeller, and increases propulsion at the same time, boosting fuel efficiency by three to five percent. Improvements to the efficiency of the PBCF system stem from the redesigned length and shape of the device. Compared with the previous model, these changes allow more reliable control of the hub vortex, boost propeller thrust, and reduce

torque. The new design features are covered in the patent application. The original PBCF patent application was filed in Japan in July 1987. Since then, the PBCF has been patented in Japan and eleven other countries. MOTech plans to install the new PBCF system on an MOL-operated vessel that will be completed at the end of 2009 and conduct performance tests. At the same time, the company will conduct research on final design and manufacturing, aiming to bring the enhanced PBCF to market in 2010. For further information :

PBCF (Propeller Boss Cap Fins) is a propeller efficiency improvement device group of companies with a focus on Mitsui OSK Lines, Ltd. has developed. To recover the hub vortex energy of the propeller slipstream of the characteristics of the PBCF, saving 5% fuel consumption at the same speed under. You can get the speed increasing effect of 2% in the same horsepower. The effect work for any marine screw propeller regardless of the type of ship, hull form, orders received topped the 1800 vessels in the world in 2009. Currently, there is a track record of patent established in 13 countries around the world, won three awards from the Society of Naval Architects, etc. In Japan, energy-saving effect of about 5% has been verified by the research institutes and ship owners in the world, including the ITTC. In addition, energy-saving effect count of 5% was observed in 12 of the year the Ministry of Land, Infrastructure and Transport in the Heisei "Ekoshippu" project. these days when global environmental protection is important, not only as the "energy saving devices", as "environmentally friendly products", more and more demand for PBCF is growing.