【作者】 马勇；

【导师】 刘祖源； 郑伟涛；

【作者基本信息】 武汉理工大学 ， 流体力学， 2009， 博士

【摘要】 本文以夏季奥运会级别帆船帆翼作为研究对象,利用数值模拟与试验方法对帆翼空气动力性能进行研究,对帆翼空气动力特性进行了全面分析,为运动员根据不同外界条件调帆提供科学依据。首先讨论了帆翼模型进行数值计算时计算区域的大小以及网格类型对于计算精度的影响,确定了帆翼远场前、左右、上取6倍帆翼底边弦长,远场后取10倍帆翼底边弦长,底部采用实际距离海平面距离;采用混合网格进行网格划分,能够得到既节省计算时间、又精度较高的模拟结果。讨论了数值计算时来流处理方式不同对于计算结果的影响,确定本论文采用来流不变而转动帆翼,重新生成网格的方法来模拟不同攻角的帆翼周围流场。讨论了不同湍流模型对于计算结果的影响,根据分析以及与试验结果比较,确定了帆翼数值模拟采用Realizableκ-ε模型。讨论了均匀风和梯度风情况下帆翼周围流场的差异,发现梯度风帆翼周围流场与均匀风差异不大,为了更加接近实际比赛情况,在数值模拟中宜采用梯度风进行数值模拟。本文对帆翼两种不同帆型的空气动力性能进行了全面讨论。通过比较,发现桅杆对于帆翼空气动力特性影响较大,在比赛中尽量选用可调整的流线型的桅杆。讨论了不同扣角和倾角对于帆翼空气动力特性影响。研究发现向内扣角尽管升力系数也相应减小,但是其垂直水平面向上的力会增加很大,这对于减小船体阻力,提高帆船速度有利。帆翼后倾有利于提高帆翼的升力系数,对于提高帆船速度有利。讨论了两种不同帆型的空气动力特性,发现拱度较大的帆翼其升力系数较大,对于提高帆船速度有利,但是其倾斜力矩增加了,其压力中心也增加了。所以,综合考虑帆船整体行驶性能情况下,一般大风用拱度较小的帆翼,小风中使用拱度较大的帆翼。本文利用风洞试验进行了帆翼空气动力性能研究,通过改变帆翼的攻角,得到在不同航向角帆翼的空气动力性能数据及曲线,其结果与实际基本吻合。根据计算与试验结果,比较了两种不同帆型在不同航向角下推力系数、侧向力系数,得到了不同帆型在不同航向角下帆翼的最佳攻角范围。讨论了两种不同帆翼推力系数和侧向力系数在不同航向角下随攻角变化情况。分析了不同航向角下最大推力系数以及对应的侧向力系数,得到了帆翼在所有航向角下最大的推力系数以及对应的操帆角。同时讨论了两种帆型不同航向角下第二大推力系数及对应的侧向力系数。最后,根据数值模拟和试验方法得到的帆翼空气动力性能特点,详细系统介绍了在起航航段、迎风航段、横风和侧顺风航段、尾风航段、终点线前航段和各标旁附近帆翼调整方法。运动员应该掌握各航段上调帆的基本原则并应用于实践中,最终的目的是战胜对手,取得优异的成绩。本论文研究成果在备战2008年北京奥运会期间应用到中国国家帆船队训练、比赛实践中,为我国帆船夺得一枚宝贵的铜牌、实现我国帆船项目奥运会奖牌零的突破做出了贡献。更多还原

【Abstract】 By use of the numerical simulation and experimental method, the aerodynamic performance of the sail in the Olympic Games was studied and analyzed. The results of the research could supervise the athletes to trim the sails based on the condition.It’s discussed how the district and grid of the numerical simulation could affect the precision of the results. If the district would be six times of the chord of the sail bottom on the ahead, left, right and up direction, ten times of the chord of the sail bottom and the grid would be mixed, the precision could be good and the time could be saved. It’s discussed how the inlet modes affected the results. In this article, when the aerodynamic performance of the sail was studied by the numerical simulation, the inlet direction was immobile and the sail was turned, the grid of the district was constructed. The article studied how the turbulence model affected the precision of the results. Five different turbulence models were used on the sails. Based on the theoretical analysis and the compare with the experimental results, the realizable k -εmodel was the best in terms of the both accuracy and robustness, and this model was used to predict the aerodynamic performance of the sails. The difference of the flow field under the uniform and gradient wind was analyzed. It’s found that there was different, but the difference was small between the uniform and gradient wind. Due to the practice condition, the gradient wind was used.The aerodynamic performance of two sails was discussed. It’s found that the mast affected the aerodynamic performance of the sails obviously and the streamline mast should be used on the game. The different pitch of the sail affected the aerodynamic performance. If the sail was pitched with the direction of the athlete, the lift coefficient would decrease, but the upward force coefficient would enhance awfully. So, it would be propitious to decrease the resistance of the hull and enhance the speed of the sailing. The pitch with the direction of the stern would enhance the lift coefficient of the sails and the speed of the sailing. By compare with the aerodynamic performance of two sails, it’s found that the lift coefficient would be bigger and the speed of the sailing would be enhanced, but the drag coefficient of the sail would also enhance if the camber ratio of the sail was higher. So, if the whole performance of the sail would be considered, the smaller camber ratio would be used on the strong wind and the bigger camber ration should be used on the light wind.The aerodynamic performance of the sail was studied by the experiment method in a wind tunnel. The data of the aerodynamic performance of the sail in different angle of the sailing were gained. The results were accordant with the practice.Based on the results of the numerical simulation and experimental method, the thrust and side force coefficients of two sails were compared. The good attack angle of the different sails was found.The trimming of the sail run through the process in the match, this article analysis the methods of the trimming during the leg of the starting, windward, downwind and the front of the finish line and the side of all the mark. The athletes should keep a firm grip on the principle of the whole leg and use them to trim the sail.The researches of the article have applied to supervise the testing and compete of the civil national sailing team and were contributed to get the copper brand and break through the brand of the civil sailing in the Olympic Games更多还原