艏外飘型船体入水砰击的二维SPH模拟

Numerical simulation of 2-D bow flare slamming using SPH method

砰击现象会导致船体局部结构受损或者会引起船体振动甚至折断,因此准确地预报船舶受到的砰击压力是水动力学研究的前沿课题之一。该文采用光滑质点水动力学方法(SPH方法)模拟具有代表性的二维外飘型船体物体入水问题,给出了艏外飘型船体的入水砰击的数值模拟结果。经与现有的实验与边界元方法计算结果比较,结果表明在低速、剖面曲率变化较小的情况下,单相SPH方法可有效地模拟二维外飘型船体入水砰击过程。船体表面压力时间过程线和入水阻力时间过程线反映了入水砰击过程中自由表面大变形和流动形成过程的水动力学效应。并给出了在一定弗劳德数范围内,不同测点处最大压力系数与剖面受到的垂向力的最大阻力系数的变化规律。

Slamming events have the potential to cause significant structural damage and hull vibration even break off due to the loads and subsequent whipping experienced by the ship. It is very important for ship hydrodynamics studies to predict the slamming loads accurately. The Smoothed Particle Hydrodynamics method is applied to simulate the slamming process of a two dimensional bow flare section. Comparing with the experimental data and results of the Boundary Element Method, it turns out that, in the case of low entry speed and small changing rate of the curvature of hull section, the single phase SPH method could obtain fair results in simulating two-dimensional bow flare slamming on still water. The computed time series of the pressure and the drag on the ship hall reflect the hydrodynamic effects of the violent deformation of the free surface and the formation of flows around the ship hall. Relationships between the coefficient of maximum pressures and maximum drag acting the and the Froude number are provided for the cases of vertical water entry and inclined water entry of the flared bow.