Research on solid-liquid coupling dynamics of pipe conveying fluid

I.IntroductionSolid-fluidcouplingvibrationproblemofpipesconveyingfluidarepresencegenerallyinthedomainofastronomic,energysources,chemicalindustryetc..Notonlytheoreticallytheproblemhaswideresearchvalue,butpracticallytheproblemhaswideengineeringbackground.Therefore,itisimportantreseachproblemihsciencedomainspang.Thefirstrightequationofsolid-liquidcouplingvibrationofpipeconveyingfluidwaspiovidedbyG.W.Housner,andV.Y.Feodosievil'2].Thebasicfrequencycharacteristicofpipesconveyingfluidwasstudiedre…     

K－ε模型在复杂管流中的模拟计算

本文对复杂管流中的湍流问题采用了k-ε模型进行模拟计算.对于复杂边界问题采用了阶梯型网格近似,取得了较好的结果.文中给出了两例复杂管流的计算算例,说明了K-ε模型具有很强的适应性和稳定性.     

垂直管道中密相两相流动的解析解

本文依据文献[1]的密相两相流动的数学模型,对垂直圆管中密相两相流动进行了解析求解,分别得到了连续相和分散相的速度解析表达式.在相间阻力与相间速度差成比例时,除了在离管壁面很近的薄区之外,管道流动规律与达西渗流定律完全一致.本文验证了文献[1]的密相两相流动数学模型的假定在本文情形下是合理的.     

A hybrid/mixed model finite element analysis for eigenvalue problem of moderately thick plates

The buckling and free vibration problems of moderately thick plate are considered in this paper by using the hybrid/mixed finite element model. A modified Reissner principle which only requires C⁰ continuity is derived. No lockling phenomenon is observed. Linear interpolation is used for all independent unknown function. Finally a displacement generalized eigenvalue equation is obtained, in which the stiffness matrix is symmetric and positively definite. The calculated results show that the method proposed is simple, reliable and satisfactory.     

非交换无色散Gelfand-Dickey方程族的附加对称

本文主要研究非交换无色散Gelfand-Dickey (GD)方程族的附加对称, 给出它的Lax函数及方程, 定义Orlov-Schulman函数和附加流. 在GD方程族约束情况下, 找出非交换无色散GD方程族附加流中的存活流, 同时研究特殊流得到弦方程并证明其形成一个无穷维李代数.     

清管载荷作用下输气管道安全落差研究

山地天然气管道局部落差和坡度大,在清管过程中易在清管器冲击载荷作用下发生屈曲和应力超限.基于有限元方法研究了考虑管-土耦合作用的大落差管段清管过程非线性动力学特征,分析了清管器运行速度、管道坡度、清管器-管内壁间摩擦系数对管道受力和位移的影响,得到了不同坡度、摩擦系数条件下极限清管运行速度和最大高程差.结果表明:清管器...     

HEAT-PIPE-COOLED THERMAL PROTECTION FOR THE LEADING EDGE OF THE WING

针对高超声速飞行器飞行时翼前缘存在着严重的气动加热问题,为了保证翼前缘的尖锐外形,提出疏导式热防护结构,利用内置高温热管结构为翼前缘提供热防护。采用数值模拟和电弧风洞试验的方法对翼前缘疏导式结构进行了分析,得到翼前缘内置高温热管具有的防热效果。数值模拟结果表明在一定热环境条件下,翼前缘驻点温度下降了304K,尾部最低温度升高了130K,实现了热流从高温区到低温区的疏导,减弱了翼前缘的热载荷,强化了翼前缘的热防护能力。通过电弧风洞试验可以获得相同的热防护结果,并且在一定飞行条件下高温热管可以自适应启动,验证了数值模拟方法的准确性以及翼前缘内置高温热管疏导式热防护结构的可行性。     

复合材料结构力学分析CAE软件现状

复合材料结构分析软件是用以分析、设计复合材料结构的重要工具,常用的复合材料结构分析软件包括基于CAD软件发展而来的复合材料分析工具、通用有限元软件自带复合材料分析工具和以Digimat等为代表的专业化复合材料结构分析软件。本文对常用的复合材料分析软件进行了综述,介绍其主要功能,从学术、应用等多方面探讨相关产品的优点及不足;论述了专业化复合材料结构分析软件的特点及功能;分析了复合材料结构分析软件的现状和发展趋势;探讨了复合材料结构力学分析CAE软件在国产化方面所需进一步解决的问题。     

Bending-torsional stability analysis of aerodynamically covered pipes with inclined terminal nozzle and concurrent internal and external flows

Stability analysis of a cantilevered pipe with an inclined terminal nozzle as well as simultaneous internal and external fluid flows is investigated in this study. The pipe is embedded in an aerodynamic cover with negligible mass and stiffness simply to streamline the external flow and avoid vortex induced vibrations. The structure of pipe is modeled as an Euler–Bernoulli beam and effects of internal fluid flow including flow-induced inertia, Coriolis and centrifugal forces and the follower force induced by the exhausting jet are taken into account. In addition, neglecting the compressibility effect and using the unsteady Wagner model, aerodynamic loading is determined as a distributed lateral load for any generic structural state. The integral form of coupled equations of motion are obtained using the Hamilton’s principle. Solution to the coupled flexural–torsional equations of motion is realized via the extended Galerkin method. After discretization of the equations of motion, an eigenvalue representation of the problem is obtained. Several parameter studies are then conducted to examine the effects of concurrent fluid flows and other related parameters on the stability margins of the system.