Study On The Rigid Body Dynamic Model Of Broken Ice Overturning In The Bow

When considering the composition of ice resistance,we should consider the whole process of the ship from the contact with flat ice to the contact between the broken ice and the hull surface,until the broken ice sliding into the water.After the bow impacts the flat ice,smaller ice fragments will be produced.In the process of continuous navigation,the ship inevitably needs to have a second contact with the broken ice,at this time,the broken ice will overturn under the action of the hull.The overturning process of the broken ice has an important influence on the ice resistance during the contact between the broken ice and the ship.In order to study the ice resistance completely,this process is worthy of further study.In this paper,a rigid body dynamic model of broken ice overturning is established based on the geometric relationship of ship and ice and the force balance relationship of broken ice in the process of broken ice overturning,and the pressure difference characteristics of the upper and lower surfaces in the process of ice overturning are studied by CFD software.Firstly,the research methods of ice resistance are summarized,and the advantages and disadvantages of different methods are explained.At the same time,this paper mainly introduces the current situation of research on the phenomenon of Ventilation in the process of broken ice overturning,and introduces the fluid model in STAR CCM +,which is used to study the broken ice overturning motion.The broken ice overturning motion is preliminarily simulated by using square ice.On the basis of studying the process of the overturning of broken ice,the motion of the broken ice is divided into four stages: fixed-point overturning,sliding overturning,free overturning and final collision.According to the geometric relationship between ship and ice,the force balance relationship of broken ice,the rigid body dynamic model of broken ice overturning is established.Finally,it is realized by program,and the feasibility of rigid body dynamic model is verified by visualization.Based on the model,the effects of friction coefficient,ship speed and ice thickness on the overturning process and ice resistance are studied.In order to further study the hydrodynamic phenomena in the process of broken ice overturning,the overturning model of fan-shaped ice was established in STAR CCM +,and the Ventilation phenomenon in the process of broken ice overturning was successfully captured.On the basis of the model,the effects of ice breaking speed,ice thickness and the position of turning axis on hydrodynamic response during broken ice overturning are further studied.Finally,on the basis of the basic rigid body dynamic model of broken ice overturning,further considering the change of bow expansion angle caused by ship pitching,and the situation of ship accelerating motion,the rigid body dynamic model is further improved.Based on the complete model,the effects of ice thickness,friction coefficient between ship ice and initial speed on ice resistance during broken ice overturning are studied.