CFD study of ship stopping maneuver by overset grid technique

Abstract

The crowded waterways and worse maneuverability of large ships could cause more collision accidents. Therefore, it is necessary to study stopping ability of ships to ensure the navigational safety. In this paper, the CFD solver naoe-FOAM-SJTU associated with dynamic overset grid method is used to simulate several types of maneuvers of KVLCC1 ship model. Stopping maneuvers with reversing propeller, turning rudder with/without propeller are simulated to predict the ship stopping performance. Turning circle maneuver is also simulated to predict the advance and comparisons with stopping distance of other stopping maneuvers are discussed. Self-propulsion simulation is conducted firstly to validate the present CFD approach through comparisons with available experiments. Stopping maneuver simulations start from the steady state of self-propulsion, then different types of stopping maneuver is carried out by controlling the propeller and rudder. In addition, deep and shallow water conditions are both computed to illustrate the water depth effect on the stopping performance. The predicted trajectory and ship speed of different stopping maneuvers are presented and analyzed. Detail information of flow visualizations including pressure distribution and wake flow during stopping maneuver are discussed to explain the stopping behavior. It is concluded that the turning circle maneuver is the most preferable way to avoid the collision in open sea. However, if the ship needs to stop in port or waterways, then the reversing propeller (RP) is better due to the fact that it meets the relatively shorter lateral deviation.