冰区航行船舶推进器特殊性分析

  目的  为了准确评估破冰船在平整冰区航行时连续破冰过程中所受的冰阻力，同时了解不同预报方法的特点，采用经验公式法、数值模拟法以及船模试验法，对破冰船在平整冰中连续航行时的冰阻力进行预报。  方法  使用非线性有限元软件DYNA，分别基于传统有限元与黏聚单元法构造冰层数值模拟模型，模拟平整冰与破冰船相互作用时发生的弯曲断裂以及相互作用的过程。同时，采用经验公式法，用3种不同的经验公式进行冰阻力计算，对影响经验公式法预报结果的参数进行敏感性分析。  结果  研究发现：冰阻力随航速、冰厚度以及弯曲强度的增大呈上升趋势，其中冰厚对冰阻力的影响最大。3种经验公式中，Lindqvist公式的预报结果与船模试验结果更为接近，而Vance和Lewis公式更为保守。传统有限元与黏聚单元法在冰厚较小的情况下，冰阻力预报结果更准确，冰厚较大时误差较大，约25%。在冰厚较小航速较高的情况下，黏聚单元法预报的冰阻力值较传统有限元方法更为准确，与船模试验结果相比精度误差在10%以内。  结论  在实际的冰阻力预报中，可结合经验公式法与数值模拟法，兼顾预报结果的准确性与高效性。

Analysis on the particularity of propulsor of ice-going ships

  Objective  In order to accurately assess the ice resistance experienced by an icebreaker during continuous icebreaking when sailing in a level ice zone, and understand the characteristics of different prediction methods, this paper uses the empirical formula method, numerical simulation method and ship model test method to evaluate an icebreaker's continuous sailing in smooth ice and predict the ice resistance.   Method  In this paper, the nonlinear finite element software DYNA is used to construct ice numerical simulation models based on the traditional finite element and cohesive element methods respectively, and simulations are performed of the bending fracture and interaction process that occurs when level ice interacts with an icebreaker. At the same time, using the empirical formula method, three different empirical formulas are used to calculate the ice resistance, and a sensitivity analysis of the parameters affecting the prediction results of the empirical formula method is also carried out.   Results  The study finds that ice resistance shows an upward trend with the increase in speed, ice thickness and bending strength. Among them, ice thickness has the greatest influence on ice resistance. Among the three empirical formulas, the prediction results of the Lindqvist formula are closer to the ship model test results, while those of the Vance and Lewis formulas are more conservative. The traditional finite element and cohesive element methods obtain more accurate ice resistance prediction results when the thickness is small. When the thickness is large, the error is about 25%. In case of small ice thickness and high speed, the ice resistance value predicted by the cohesive element method is more accurate than that of the traditional finite element method, and the accuracy error is within 10% compared with the ship model test results.   Conclusion  In the actual ice resistance prediction, the empirical formula method and numerical simulation method can be combined to take into account the accuracy and efficiency of the prediction results.