Decreasing Frictional Resistance By Air Lubrication

SEMINAR ON AIR LUBRICATION SYSTEM 

The decrease of ship resistance is one of the most effective way to reduce operating costs and CO2 production. The wave making resistance and form drag can be reduced by optimizing the hull form, but the frictional drag remains proportional to the wetted surface. The use of air as a lubricant in order to reduce that frictional drag is an active research topic and three techniques are identified: injecting air bubbles in the boundary layer, the use of air films along the bottom plating, and using air cavities in the ship's bottom. These approaches are the research topic for the Dutch joint-research project PELS and the EU project SMOOTH, both of which have the goal of not only predicting energy savings using numerical models and model tests, but proving it using full-scale demonstrator ships adapted for air lubrication. Although decreases in frictional resistance of nearly 20% have been obtained on model-scale ships, experience shows that the implementation of air lubrication can also easily increase the resistance of a ship.

The increase in fuel costs and looming restrictions on carbon dioxide emissions are driving the ship owner into reducing the ship resistance and required installed power. The propulsive efficiency using the propeller is often good and it is difficult to gain a few percent. Thrust augmenting devices such as high-efficiency rudders and kites will undoubtedly be prevalent in the future. Reducing the required propulsive thrust is a more direct means to lower operating costs and can even be used in conjunction with thrust augmenters to further sharpen the competitive edge of the ship owner. The main components of ship resistance consist of resistance due to wave drag, pressure drag, and frictional drag. The wave and pressure (form) drag can be optimized by carefully manipulating the lines of the vessel, but frictional resistance remains proportional to the wetted surface and the square of the ship speed. As this resistance drag is by far the largest resistance component in normal operating speed ranges, any reduction of this component will have an immediate and favorable influence on the performance of the vessel. Such reductions can be achieved by compliant coatings, ribblets, polishing the surface, or polymer injection; measures that are not very practical for ships. A promising technique to obtain lower frictional resistance is using air as a lubricant to reduce the wetted surface of the ship.

Click Here To Download Full Seminar Kit

Key:Seminar report Air lubrication system,Seminar on air lubrication system,application of air lubrication,Air lubrication in tribology,Seminar on tribology,Air lubrication ppt,Air lubrication system pdf,Seminar on air lubrication in machines,Working and applications of air lubrication system,International seminar report download,mechanical engineering seminar download,new seminar topics in mechanical engineering