断级与无断级滑行艇阻力性能的数值预报

Numerical Prediction of Resistance Performance of Stepped and Non-stepped Planning Craft

基于重叠网格技术对Taunton系列中的断级与无断级滑行艇在不同航速下的船舶绕流场进行,结合试验数据与相关流场信息比较两种滑行艇的阻力性能差别,分析表明,造成阻力预报误差的主要原因是由于VOF方法不能很好捕捉自由面产生的强非线性的飞溅现象,无法有效的将飞溅阻力记入总阻力当中;对中纵剖面水气分布可知,断级滑行艇阻力性能优于无断级滑行艇的根本原因是断级位置处滑行面的不连续导致空气从断级处进入形成断级后“空穴”,减少了浸湿面积降低了摩擦阻力,随着航速的提升空穴面积也逐渐增加,减阻效果也愈加明显。

The overlapping grid technology was used to numerically simulate the flow field of the ship in different stages of the Taunton series and step planning crafts at different speeds.The difference in resistance performance between stepped and non-stepped planning crafts was compared with test data and related flow field information.It was shown that the main reason for the error of resistance prediction is that the VOF method cannot capture the strong non-linear splash phenomenon on the free surface,and it cannot effectively record the splash resistance and the total resistance,which results in the resistance prediction error.Comparison of the water and gas distribution in the middle profile of stepped and non-stepped planning crafts showed that the fundamental reason for the resistance performance of the step planning crafts is better than that of the non-step planning crafts;the"cavity"after the failure step reduces the wetted area and reduces the friction resistance.As the speed increases,the cavity area gradually increases,and the drag reduction effect becomes more and more obvious.