Estimation of ice resistance and sensitivity analysis for an icebreaker

The Lindqvist method is adopted to estimate the ice resistance for an icebreaker.The accuracy of the method is evaluated in a comparison of the calculated results with model test results.In addition to the estimation of ice resistance,a sensitivity analysis based on the Lindqvist method is carried out.A full parametric model developed using CAESES software allows the convenient construction of many new hull lines.The primary factors relevant to ice resistance are embedded as design parameters in the full parametric model.Meanwhile,response surface methodology is adopted to give better insight into new hull lines.Results show that the ice resistance is more sensitive to the rake angle and waterline entrance angle.The aim of the present study is to improve the techniques of designing the hull forms of icebreakers.

内河破冰船实船振动试验研究

A series of tests of a full-scale river icebreaker was conducted to investigate the characteristics of ice-induced hull vibration.The test was conducted when the river icebreaker was operating in an ice-covered river at temperatures of-4 to 0°C with ice thicknesses of 300 to 400 mm.In the tests,the ice condition and icebreaker speed were chosen as the main influence factors.By analyzing the measured test data,we identified some important points regarding ice-induced hull vibration.When the river icebreaker navigates in an area with complete ice coverage,the peak value of the acceleration amplitude spectrum is highest.Also,the vibration response excited by the icebreaking load in an area with complete ice coverage exhibits more frequencies.With an increase in icebreaker speed,the vibration acceleration response gradually increases.However,habitability of the bow region on the main and driving decks is maintained due to the harmless vibration levels.In addition,the icebreaking operation of the river icebreaker causes violent local vibration of the grillage on the main deck.

硬帆辅助推进散货船的稳定性和动力性能综合分析

Large size vessels sailing in continuous level ice and broken ice of high concentration are mostly assisted by icebreakers.This is done in order to provide for fast transportation through the North Sea Route and safe operation in extreme ice conditions.Currently,new large size gas and oil carriers and container ships are being designed and built with beams much greater than the beams of existing icebreakers.At the same time,no mathematical description exists for the breaking mechanism of ice channel edges,when such vessels move under icebreaker escort.This paper suggests a simple method for assessment of the ice resistance in the case of a large ship running in an icebreaker channel;the method is based on modification of well-known semi-empirical methods for calculation of the ice resistance to ships in level and broken ice.The main feature of the proposed calculation scheme consists in that different methods are applied to estimate the ice resistance in broken ice and due to breaking of level ice edges.The combination of these methods gives a deliverable ice resistance of a large size vessel moving under icebreaker assistance in a newly made ice channel.In general,proposed method allows to define the speed of a carrier moving in an ice channel behind a modern linear icebreaker and could be applied at the ship design stage and during development of the marine transportation system.The paper also discusses the ways for further refinement of the assessment procedure suggested.

基于光滑粒子流体动力学方法的黄河破冰船破冰阻力数值方法研究

A ship-ice-water interaction model is established using smoothed-particle hydrodynamics(SPH)to predict the ice breaking resistance of the icebreaker in the Yellow River effectively.This method includes the numerical process of the constitutive equation,yield criterion,and the coupling model in SPH.The ice breaking resistance is determined under different conditions.The numerical results of the ice breaking resistance agree with the empirical formula results.Results show that the prediction accuracy of ice resistance is less than 17.6%compared with the empirical formula in the level ice.The method can also be extended to predict the floe motion and ice breaking resistance in actual river channels.The validation against the empirical formula indicates that the proposed ship-ice-water SPH method can predict the ice breaking resistance of icebreakers in actual rivers effectively.The predicted ice breaking resistance is analyzed under different conditions.The ice breaking resistance increases with increasing bending strength and ice thickness,and the latter is the most important factor influencing ice resistance.

VANINO冰区航行纪实

本文通过介绍船舶在俄罗斯VANINO冰区航行实践,以及与冰区引航员的交流探讨,总结出在严重冰况下冰区航行的相关经验,包括对接近冰区的船舶提出警示、对冰量逐渐增大的冰区航行应果断舍弃传统的沿岸航行航法、提前向代理索取海上冰况图(sea ice condition chart)、走推荐航路等,并针对冰区船舶的航行靠离泊等方面提出了相关的注意事项,为船舶在俄罗斯冰区的安全航行提供经验参考。

Problem statement on the vessel braking within ice channel

Sailing within the ice channel that assisting icebreaker tracks is usual for difficult ice conditions in the Northern freezing seas and the Arctic region.There is the danger of emergency,namely,the collision with an icebreaker or the ahead vessel,when ones stop before insuperable ice obstacle or because the engine trouble.The paper contents analysis of the vessel braking process and formulation of the equation that gives possibility modelling this process and evaluating the distance that is necessary for safe stopping of vessel in dependence on its characteristics and ice conditions.Outcomes of investigation will be applicable for the caravan of cargo vessels forming while the icebreaker assistance.

ICEBREAKING MISSION

Vehicles carrying members of China’s 35th Antarctic research mission on their way to the Zhongshan Station,a Chinese research base in Antarctica,on February 8.The scientists,including 21 from the Taishan team and 16 from the Kunlun team,have successfully completed their research tasks.The Taishan team completed construction of the supporting facilities.