三体滑行艇FPM流场精细模拟及空穴减阻机理研究

High-speed ship form optimization is a key problem in the field of shipbuilding engineering, and become an important research direction of civil ship and naval equipment. At high speed sailing, the splash is produced around the trimaran planning hull, the air-water mixtures get into the channels, the air cavity formed behind step, a lot of water vapor particles point in a discrete state forming complex votex flow. The traditional CFD numerical algorithms have a great difficulty in dealing with a large number of discrete particle and complex boundary conditions. With the development of the meshless method and its good adaptability, it offers new possibilities for the simulation of trimaran planning hull flow. This project is based on the research of Finite Pointset Method(FPM), a point cloud optimization method and a proper boundary model are introduced into FPM which can improve the algorithm accuracy and boundary processing capacity, so that the algorithm can effectively simulate the nonlinear mixed flow in the channel and the air cavity behind step. Through the model test, the high-speed trimaran planning hull hydrodynamic performance prediction method can be established. Based on FPM we can summarize the influence of channel and step for trimaran planning hull flow field, explore the high- speed stability, research on mechanism of drag reduction of Air Cavity and the optimization design of step, which provides an important theoretical guidance in the ship optimization design field.

高速船是船舶工程领域的重点问题，是民用船舶和海军装备发展的重要研究方向。三体滑行艇在高速滑行时，船体周围产生飞溅，槽道内高压气水混合流形成气膜，艇底断级后形成空穴，大量水气粒子点处于离散状态并形成复杂的涡旋流动。传统的船舶水动力研究方法在处理这种具有大量离散质点和复杂边界条件的气水混合流动上存在明显不足，随着无网格计算方法的迅速发展和其良好的适应性，为精细模拟三体滑行艇流场提供了新的途径。本项目在现有的有限点集法研究基础上，引进适当的点云优化方法及槽道边界模型，提高算法精度和边界处理能力，使该算法能够有效模拟三体滑行艇槽道内气水混合介质的非线性流动及断级后空穴形态变化。通过船模试验对数值方法进行验证，建立高速三体滑行艇水动力性能预报方法。基于FPM总结槽道及断级对三体滑行艇流场变化的影响规律，探索高速三体滑行艇纵向运动稳定性，研究空穴减阻机理，开展断级优化设计，为船型优化设计提供理论指导。

高速三体滑行艇是一种具有超高航速、良好的稳定性能、出色的适航性和高运载效率的新型船型，它将多体船、滑行艇、气膜减阻船等多种船型原理结合于一体。本项目针对其独特的水/气动力性能，采用理论计算方法与模型试验手段进行了三体滑行艇构型设计、水/气动力机理的研究及船型优化，获得了一定的研究成果。.在基本研究手段上，开展FPM数值计算方法的研究，通过数值计算中粒子点云的处理和优化、移动最小二乘法的精度校验、经典二维三维算例验证、三维绕船流FPM方法数值求解及模型对比，提出了适用于模拟高速水气混合流动特性的水动力性能预报方法。以数值仿真为手段对槽道减阻机理进行了分析，研究表明随着航速的提升槽道与主体兴波逐渐脱离并进入全通气状态，在此过程中气动升力逐渐显现；实现了单目标阻力性能自动优化系统的搭建，以最大航速下静水阻力值为优化对象，以片体高度、片体下压角度、片体相对长度等几何参数为设计变量，对三体滑行艇构型进行了优化设计，研究结果表明，三体滑行艇相比于同尺度单体滑行艇在高航速下表现出了明显的阻力优势以及优异的运动稳定性；通过船模试验对数值计算精度、三体滑行艇水动力性能及断级减阻效果进行了验证。