Investigation of the excess roll problem of an emergent buoyantly rising submarine

Abstract

This paper describes the model test design conducted to investigate the effects of the pitch angle, yaw angle, static metacentric height, and flooding hole on the excess roll problem of an emergent buoyantly rising submarine. An increase in the pitch angle can decrease the roll angle prior to surfacing, but will decrease the metacentric height when emerging through the water surface. There was a slight effect of the static metacentric height on the excess roll problem when the submarine had a considerable initial forward speed. The metacentric height of the neck decreased significantly when the area of the flooding hole decreased, but there was only a slight effect of flooding holes near the middle body. The maximum roll and maximum yaw angles were positively correlated. Based on the results from using a computational fluid dynamic (CFD) method to study the coupling and interactions between the roll, yaw, and sway, the rolling moment increased with the increasing velocity and drift angle, and the yawing moment increased with the increasing velocity and roll angle. We also found that the sail accounted for approximately 70% of the rolling moment and 30% of the yawing moment for a rising submarine. The main source of the rolling moment was from the sway velocity on the sail, and the sway velocity and the drift angle were positively correlated with the yaw velocity; thus, the yaw angle must be limited to as small as possible to decrease the maximum roll angle.