Numerical Prediction Of Level Ice Resistance Of Icebreaker By Two-dimensional Discrete Method

Ice load is the main load of ships sailing in ice area.It is very important to estimate the overall and local ice load on icebreakers to study the navigation performance of icebreakers in ice areas.In this paper,according to the continuous ice-breaking process,the numerical simulation of the ice-breaking process is carried out by using programming language,and the influence of the change of the bow ’of the icebreaker on the ice-breaking process is studied and analyzed with the help of LS-DYNA software.The main contents of this paper include:1.Based on the summary of some physical and mechanical properties of sea ice,the ice-breaking model of icebreaker is analyzed and studied,and a series of idealized assumptions are made to simplify the ice-breaking process.2.The numerical theory involved in the ice-breaking process is described in detail,and the discrete two-dimensional model of ice-breaking movement of icebreaker is established.According to the simplified continuous ice breaking process,the movement process of.the icebreaker under the ice layer condition under the ideal condition is simulated by programming language,the breaking force is calculated,and the complete flow chart of the breaking force algorithm is established.On this basis,considering the immersion resistance caused by the ice breaking movement in the bow,the breaking force is modified,the modified ice breaking resistance is calculated,and the ice resistance curve of the icebreaker in the ice breaking process is obtained.3.The Spencer algorithm,Lindqvist algorithm and Riska algorithm are sorted out,and the VB language is used to program,and the ice resistance calculation software based on empirical formula is compiled.The results of empirical algorithm and numerical simulation are compared and analyzed.Determine the value of the empirical parameters in the numerical calculation,and analyze the influence of the change of the empirical parameters on the numerical calculation.At the same time,the accuracy of the numerical simulation results is verified,and the shape of the sea ice after bending and falling off in the ice breaking process and the ice breaking time curve under different ice thickness are calculated and analyzed.The results show that the numerical method considering the immersion resistance is more accurate and reliable,and the ice-breaking resistance increases with the increase of ship speed and ice thickness,in which the ice thickness hi has a more significant effect on.the ice-breaking resistance.4.In order to explore the influence of bow column inclination angle and waterline angle on ice-breaking resistance,a triangular prism model is established to simulate the change of bow angle,the top angle of triangular prism is used to simulate the change of waterline angle,and the angle between triangular prism and layer ice is used to simulate the change of bow column inclination angle.a three-prism-layer ice motion model is established.In order to explore the relationship between the size of the model and the ice-breaking resistance,the model is scaled up by twice as much as the original model,and the calculated results are compared with those of the original model.The results show that when the model is enlarged by one time,the ice-breaking resistance is about 2 times that of the original model,the increase of waterline angle will cause the increase rate of ice-breaking resistance,and there is an optimal angle considering the bow column inclination angle.