Numerical Study on A Planning Hull to Improve the Sea Water Intake at High Speed

Proper functioning of certain critical systems like cooling of the main machinery and diesel alternator at various operating speed regimes on high-speed vessels, largely depends on the availability/flow characteristics of seawater at the sea chest (used as a coolant). The general practice is to provide sea tubes /sea chests in the underwater hull for intake of seawater. However, in high-speed planning vessels, the appropriate positioning of the sea chest along with the sea tube with a positive pressure gradient at the mouth of the sea tube becomes the vital parameter that influences the effective intake of seawater. In a high-speed planning vessel, which is designed to operate at various planning modes,(the majority of the hull is hydrodynamically lifted from the sea) the pressure developed at the entry of the sea tube may not be adequate for drawing seawater inside the hull. Hence this paper presents numerical analysis using RANSE solver on sea chest performance for a planning vessel at various speeds and suggest modification for improvement, such as altering the position of sea tube, dimension of sea chest, and also retrofitting a scoop element for improving the flow characteristics. The results are analyzed for the pressure developed in each of the above cases for favorable effect on the seawater intake system.