Fluid sloshing thermo-mechanical characteristic in a cryogenic fuel storage tank under different gravity acceleration levels

Fluid sloshing usually causes serious safety issues on the dynamic stability and propellant thermal management during the powered-flight phase of launch vehicle. With the wide using of cryogenic propellants, the coupled thermo-mechanical performance during fluid sloshing becomes more prominent. In the present study, one numerical model is established to simulate fluid sloshing by using the VOF method coupled with the mesh motion treatment. The phase change occurring within the tank is considered. Both the experimental validation and mesh sensitivity analysis are made. It shows that present numerical model is acceptable. Based on the developed numerical model, the effect of different super gravity accelerations on fluid sloshing hydrodynamic characteristic is numerically researched. The fluid pressure variation, the sloshing force and sloshing moment, the interface dynamic response and the interface shape variation are investigated, respectively. It shows that the gravity acceleration has caused obvious influences on fluid sloshing characteristic. When the gravity acceleration is higher than 4g₀, fluid sloshing becomes more obvious and must be paid enough attention. With some valuable conclusions obtained, the present work is of great significance for in-depth understanding of fluid sloshing mechanism.     

堆本体抗震试验动力相似关系推导与验证

为确保堆本体抗震试验中流体对流效应、脉冲效应和堆本体结构响应的准确性，需保证重力、流体与固体惯性力、结构弹性力和结构应变的相似性。本文从固体结构的振动方程、不可压牛顿流体的动力学方程、流固交界面的边界条件和环形柱体域内液体线性晃动的动力学公式出发，基于控制方程的量纲分析法，推导了考虑液体晃动效应的堆本体地震响应动力相似关系。基于上述相似关系建立了堆容器堆内构件和堆容器内自由液面流体域的缩尺模型，通过有限体积法分析堆容器堆内构件原型和缩尺模型中液体的晃动固有频率、晃动波高、压力以及液体晃动对堆容器支承裙的倾覆力矩。结果表明本文动力相似关系具有合理性和准确性，可用于堆本体缩尺模型的抗震试验研究。     

破浪板对FPSO大型LPG储罐晃动的抑制作用

为缓和浮式生产储卸油装置(Floating Production Storage and Offloading,FPSO)晃动时液化石油气(Liquefied Petroleum Gas,LPG)大型储罐内的液体介质对壳体的冲击影响,在LPG储罐内设置破浪板。采用计算流体力学(Computational Fluid Dynamics,CFD)软件分析破浪板对流体晃动的抑制作用并进行受力计算。利用流体体积(Volume of Fluid,VOF)气液两相模型建立六面体与四面体网格混合划分模型,通过CFD的动网格功能模拟船体晃动。结果表明,选取的数值计算模型与试验结果吻合较好。数值模拟结果表明设置破浪板能够有效降低晃动幅度,稳定气液界面,稳定压力分布和波动,减小罐体受液体冲击力,从而确保LPG储罐在FPSO上的使用安全。     

航天器贮箱液体的有效转动惯量(上)

分析整理了航天器圆环筒形平底贮箱内液体的有效转动惯量计算方法,修正了现有文献中的错误,在常用的参数范围内对液体的有效转动惯量进行了计算,对其变化规律和影响因素做了物理分析,推导了液体滚转有效转动惯量的计算公式,并给出了适用的近似计算方法.对于纵向挡板引起的液体滚转有效转动惯量,给出了工程计算方法,能够确定滚转时液体的有...     

Three-Dimensional Analysis Method for Sloshing Behavior of Fast Breeder Reactor and Its Application to Uni- and Multi-Vessel Type FBRs

A three-dimensional analysis method for sloshing behavior of fast breeder reactor (FBRs) is developed. The method treats the coolant in a reactor vessel as a potential flow with moving liquid surfaces. The Laplace equation of a velocity potential is solved by a boundary element method with its boundary condition described by a Bernoulli equation.

The vibration test results of a rectangular water pool are calculated by the method. Then, the method is applied to analysis of sloshing behavior of uni- and multi-vessel type FBRs. The latter consists of vessels for the core, heat exchangers and pumps. These vessels are connected by piping. In the case of the uni-vessel type FBR, heat exchangers and pumps are placed in the reactor vessel. The characteristics of sloshing behavior of both the reactors are presented.     

采用组合质量-弹簧模型的快堆卧式贮钠罐晃动分析

在核电工程中广泛使用各类形式的储液容器,储液容器的抗震分析必须考虑液体晃动的影响。针对矩形储液容器,不同于传统的单向质量-弹簧模型将液体晃动对容器侧壁、底部的作用都等效为对侧壁的作用,本文提出一种组合质量-弹簧模型及计算公式,模拟了液体晃动分别对容器的侧壁、底部的作用。组合质量-弹簧模型在三维有限元模型上的加载位置更加合理,容器底部的应力结果更加真实。利用组合质量-弹簧模型对中国实验快堆的卧式贮钠罐进行横向晃动有限元计算,算例表明了计算结果的可靠性。组合质量-弹簧模型为储液容器的有限元抗震分析提供了一种有效的方法。     

NUMERICAL SIMULATION OF SLOSHING IN RECTANGULAR TANK WITH VOF BASED ON UNSTRUCTURED GRIDS

A new method for sloshing simulation in a sway tank is present, in which the two phase interface is treated as a physical discontinuity, which can be captured by a well-designed high order scheme. Based on Normalized Variable Diagram (NVD), a high order discretization scheme with unstructured grids is realized, together with a numerical method for free surface flow with a fixed grid. This method is implemented in an in-house code General Transport Equation Analyzer (GTEA) which is an unstructured grids finite volume solver. The present method is first validated by available analytical solutions. A simulation for a 2-D rectangular tank at different excitation frequencies of the sway is carried out. A comparison with experimental data in literature and results obtained by commercial software CFX shows that the sloshing load on the monitor points agrees well with the experimental data, with the same grids, and the present method gives better results on the secondary peak. It is shown that the present method can simulate the free surface overturning and breakup phenomena.     

液体晃动的谐波响应分析

研究了箱体内液体大幅角晃动的谐波响应问题,提出了谐波产生的条件.通过建立谐波响应动力学模型,给出了大幅角晃动时液体晃动的总响应.研究结果表明,除应考虑经典的晃动共振基波响应外,还有必要考虑3次谐波响应.     

多孔挡板影响液体晃荡冲击压力特征的研究

船舶波浪中航行激励液舱内液体晃荡产生的激振力会导致液舱结构局部失效,从而影响船舶运动姿态,而多孔挡板可以有效避免该问题。构建了大振幅水平激励试验平台以探讨冲击压力对频率的响应规律,分析了多孔挡板在不同激励频率下冲击压力的时域和频域特征,并从挡板结构和涡旋强度方面解释冲击压力特征产生差异的原因。结果表明,大振幅激励下的波浪翻卷、破碎等非线性特征会导致共振频率偏离固有频率;多孔挡板能够降低液体晃荡冲击压力的峰值与峰宽,且在一阶固有频率处压力峰值降低率更显著;多孔挡板不改变幅频中的主频成分,时频谱中仅有能量较低的低频成分;多孔挡板的固体结构阻碍行进波中大部分流体运动,剩余小部分流体通过孔隙会产生涡旋运动,从而耗散能量,减缓流体对液舱壁面的冲击。