Slamming Numerical Simulation Of Trimaran With Small Side Hull In Sailing State

In this paper,a certain trimaran 3-D slamming model is built for numerical simulation analysis and dynamic mesh technique is used for achieve the sailing simulation at a certain speed in FLUENT.Then we obtain the slamming pressure distribution of main body,lateral body and cross structure,the variation of flow field near the trimaran could also be observed.Finally the dynamic response under slamming would be analyzed on the basis of flow field and pressure variation.The result of numerical simulation shows that this slamming model can describe the pressure characteristics on each part of the body and variation of the flow field pretty well during the slamming,which can provide reference to the follow-up modeling experiments.During the slamming of trimaran,the bow of main hull and side hull suffer a big slamming pressure.The bow of side hull and the area which is beneath the cross structure and near the side hull would be influenced by the second slamming caused by the later flow and cause the extra pressure peak.In addition,the slamming pressure on the bottom of the cross structure has a wide distribution and big value.These part of the trimaran have a higher requirement of loading capacity.In order to reduce the slamming pressure nearby the bow of side hull,we propose a new layout method of side hull.Based on the original model,we adjust the deflection angle of side hull in the horizontal direction and accordingly design several projects to optimize layout of side hull.By running numerical simulation of these projects,we obtain the distribution and variation of slamming pressure on the side hull in different speed,compare and analyze the characteristics of dynamic response nearby the side hull between different conditions.The result of numerical simulation shows that it's helpful to reduce the biggest slamming pressure on the bow of side hull by adjusting the deflection angle of side hull in the horizontal direction.What's more,we find a certain deflection angle for this certain trimaran as a best prioritization scheme.For the sake of researching slamming movement of trimaran further under actual wave condition,we use STAR-CCM+ to build the 3D slamming model of trimaran.By using overlapping mesh method and Six Degrees of Freedom System of Boat,we run slamming numerical simulation in different wave length,wave height and speed.Then we compare and analyze the movement response and slamming characteristics of hull structure and the result shows that the speed has a great influence on slamming pressure while the wave length and wave height have less influence but also pivotal.