Study on the water falling impact flow field and motion characteristics of vehicle with boost floatation aids in wave environment
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摘要: 为探究波浪环境下带助浮装置航行体下落冲击过程中的流场以及运动演化特性,基于CFD(computational fluid dynamics)数值模拟技术,在方法上耦合了VOF(volume of fluid)多相流模型,k-ω SST湍流模型,Schnerr-Sauer空化模型以及Stokes五阶非线性波理论,建立了一套可靠有效的数值计算方法。对水平圆柱下落入水过程进行数值模拟,试验与数值结果在下落位移上对比差异较小,验证了入水冲击数值方法的有效性。采用速度边界数值造波方法获得的造波结果与Stokes五阶非线性波理论吻合性较好。基于构建的数值方法,在不同波浪海况环境下对带助浮装置航行体下落入水冲击过程进行数值模拟,分析冲击过程中航行体的运动学参数,动力学参数以及入水空泡流场演化过程,总结了波浪环境下带助浮装置航行体的入水冲击特性。结果表明波浪环境对下落冲击过程的影响主要体现在运动衰减段,水平方向的冲击相较于垂直方向的冲击受到波浪环境的影响要大得多,不同海况对航行体的水平冲击造成的影响主要是通过影响入水空泡的形成与溃灭过程实现的。计算得到的带助浮装置航行体冲击过程位移,速度,加速度以及助浮装置受力数据为航行体波浪环境中落水回收的结构设计与安全试验指导提供了参考依据。
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关键词:
Abstract: Based on the computational fluid dynamics (CFD) numerical methods, a set of reliable and effective numerical methods for investigating the flow field and evolution characteristics of motion during the falling impact of water falling vehicle with boost floatation aids in wave environment was established by coupling with volume of fluid (VOF) multiphase flow model, k-ω SST turbulence model, Schnerr-Sauer cavitation model and Stokes fifth-order nonlinear wave theory. The numerical simulation of the process of falling into water under a horizontal cylinder showed that the difference between the experimental results and the numerical results in falling displacement was small, which verifies the validity of the numerical method of water falling impact. The wave generation results obtained by the velocity boundary numerical wave generation method were in good agreement with Stokes fifth-order nonlinear wave theory. Based on the established numerical method, numerical simulation was carried out on the water falling impact process of the vehicle with boost floatation aids under different wave sea states. The kinematic and dynamic parameters of the vehicle and evolution of water-entry cavity flow field during the impact process were analyzed, and the water falling impact characteristics of the vehicle with boost floatation aids under wave environment were summarized. The results show that the impact of wave environment on the falling impact process is mainly reflected in the motion attenuation section. The horizontal impact is much more affected by the wave environment than the vertical impact and the influence of different sea conditions on the horizontal impact of the vehicle is mainly achieved by influencing the formation and collapse of the water-entry cavity. The calculated displacement, velocity, acceleration and boost floatation aids force during the impact process of vehicle with boost floatation aids can be provided as a reference for the structural design and safety test guidance of the vehicle recovery under wave environment.-
Key words:
- vehicle with boost floatation aids /
- water entry impact /
- impact load /
- wave load
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