气体粘滞流流导计算的意见

指出现行的气体流导计算公式十分混乱，难以在真空工程中使用，建议修正气体流导定义，并重新理顺气体流导公式。     

螺旋槽式牵引泵过渡流态抽气特性的直接蒙特卡洛模拟

为研究螺旋槽式牵引分子泵(DMP)过渡流态下的抽气特性,采用直接模拟蒙特卡罗(DSMC)方法对抽气通道内的流动规律进行了数值模拟.通过数值模拟,考察了抽气通道几何参数:入口、出口槽深,槽长,螺旋升角以及螺旋槽数量与泵抽气特性参数:传输几率的关系.模拟结果表明:增加抽气通道入口槽深可提高泵的抽速;出口槽深、螺旋倾角均存在最佳值,可获得大的抽速和压缩比;延长槽长、增加槽数对抽速影响不大,可以提高压缩比.本文的研究结果表明,直接模拟蒙特卡罗方法可以较好地模拟牵引分子泵三维抽气通道内过渡流态的流动特性,可用于优化设计抽气通道几何参数,提高牵引分子泵的抽气性能.     

螺旋槽管直管和盘旋螺旋槽管的换热性能比较

螺旋槽管是一种优良的双面强化换热管,目前国内外的研究主要集中于单头螺旋槽管的研究。采用数值模拟的方法分别研究了六头螺旋槽管直管和盘旋螺旋槽管内的换热性能。基于简化了的截面形状采用UG和Gambit对上述两类管分别进行了物理造型,并以Fluent6.3为计算工具采用realizablek-ε湍流模型对两者分别进行了数值计算并对模拟结果进行了分析和比较。     

矩形截面槽牵引分子泵分子流态下抽气特性的研究

本文对常见的矩形槽牵引泵在分子流态下的通道抽气机理进行了分析，建立了计算牵引泵抽气特性的数学模型，给出了等槽宽变槽深矩形牵引通道抽气特性的计算方法，对改进分子泵的设计具有实际意义。     

基于CFD-DEM耦合的固定床管式反应器流体流动特性数值模拟

采用计算流体力学(CFD)-离散单元法(DEM)耦合法对催化剂颗粒堆积密度不同的固定床管式反应器内部的流体流动特性进行数值模拟,探索流体在通过床层时速度场、压力场的分布规律。结果表明:增大颗粒下落的初始速度能够增大床层的堆积密度,采用5 m/s的初速度堆积的床层比以自身重力自由填充的床层堆积更多的颗粒,床层的孔隙率减小了6.64%,床层的堆积密度增大了5.48%;堆积密度的增大可使床层的压力降最多增加44.29%,使介质在床层内的停留时间增加,接触时间延长。     

基于Herschel-Bulkley流变模型的自密实混凝土流动的CFD模拟

为研究和预测自密实混凝土在模板中的流动性能,该文使用了一种基于Herschel-Bulkley流变模型的CFD(Computational Fluid Dynamics)模拟方法对自密实混凝土在自重作用下的浇筑过程进行二维和三维模拟并与实验室L型箱流动达到特定位置的流动时间和流动形态进行对比,分析结果表明:H-B模型用于自密实混凝土的流动模拟是可行的,与基于宾汉模型的二维模拟结果相比Herschel-Bulkley流变模型具有更高的准确度。该文最后对二维和三维模拟方法的特点和局限进行了讨论并提出建议。     

应用CFD优化螺旋卷式膜组件流道结构

为探究螺旋卷式膜组件流道结构对流体流动和膜组件分离性能的影响,在对螺旋卷式膜组件中流体流动分离过程进行分析后,对膜组件内含有隔网的流道进行简化建模,利用计算流体力学(CFD)方法对流体在流道中的流动分离情况进行三维模拟计算.以隔网编织方式为变量,考察不同隔网编织方式下流体的流动状态和二氧化碳分离传质效果以确定较优的隔网编织方式.结果表明,隔网编织方式通过影响膜组件流道结构进而改变流体流动形态、剪应力分布、速度分布和压力分布.采用部分编织型隔网时,流体流动压降约为60 Pa/m,二氧化碳分离效率为90%左右,可以同时实现膜组件较优的分离性能和较低的流动压降.     

粘滞流体阻尼墙对平面不规则结构的扭转效应控制研究

平面不规则结构由于平扭耦联会使边界处的位移较规则结构增大很多,而给结构配置阻尼器是减小平面不规则结构边界位移的有效途径,该文将耗能效率较高的粘滞流体阻尼墙应用于控制平面不规则结构的扭转响应,研究阻尼墙控制结构扭转效应的机理及控制结构扭转的优化布置。将减震系统刚度矩阵转换到结构的质量中心,将配置阻尼墙后形成阻尼中心的阻尼矩阵转换到质量中心,从而建立可以考虑扭转效应和附加阻尼位置效应的非线性运动控制方程,并根据响应结果推导出结构位移比的表达式;利用运动方程研究阻尼中心的位置、阻尼力的大小、阻尼参数等对结构扭转效应的影响规律,结合结构位移比的表达式提出阻尼墙的平面配置原则和最优阻尼参数的取值方法。以某L型高层建筑为工程背景,根据上述原则配置阻尼墙并选取阻尼参数,并对减震体系在最不利地震动输入方向上进行非线性时程分析,分析结果表明通过合理配置粘滞阻尼墙,L型结构的扭转响应得到了有效的控制,结构最大边界位移和位移比大大降低。该研究结果为采用阻尼墙控制不规则结构扭转效应提供了基本原则和方法,并为不规则结构的减震设计提供有益的借鉴和参考。     

粘弹流动的间断有限元模拟

针对传统有限元法求解Oldroyd-B本构方程时需加入稳定化方案的缺点,本文基于非结构网格给出了统一间断有限元求解框架.该框架包含采用IPDG(interior penalty discontinuous Galerkin)求解质量方程和动量方程,与采用RKDG(RungeKutta discontinuous Galerkin)求解本构方程这两个核心.数值结果表明:该方法在求解Oldroyd-B本构方程时无需加入稳定化方案,实施比有限元法简便,且具有较高的计算精度,可有效地模拟包含应力奇异点的复杂粘弹流动问题,进而揭示非牛顿粘弹流动的基本特征.     

二维不可压无粘流动问题沿流线的有限元数值模拟

为克服二维不可压粘流动问题一般数值格式的不性和数值散现象，本文基于Ｅｕｌｅｒ方程的流函数－涡度表达式，把对流方程沿线方向的离散技术应用于涡度方程，而对流函数方程采用标准有限元逼近。论证表明，采用沿流线的离散技术，可得到在Ｌ＾∞误差估计意义下的解及对解的最优、拟最优逼近估计。     

Numerical simulation of the flow of a supersonic stream of viscous compressible gas over a cavity

Numerical simulation of the flow of a supersonic stream of viscous, compressible, heat-conducting gas over a cavity is carried out on the basis of kinetically consistent difference schemes. Different types of flow (open and closed cavities) are considered, the heat fluxes to the walls of the recess are determined, and a nonsteady regime of flow over a cavity is simulated. The results obtained are compared with known experimental relationships.Translated from Inzhenerno-fizicheskii Zhurnal, Vol. 61, No. 4, pp. 570–577, October, 1991.     

Calculating drag and heat transfer in viscous,quasistable pipe flow of supercritical helium

An integral method allowing for thermal acceleration of the flow is used to obtain data on drag and heat transfer in the laminar flow of helium at supercritical pressure in a uniformly heated circular pipe.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 44, No. 3, pp. 373–379, March, 1983.     

Transonic flow of a viscous gas in a plane-parallel channel

Results are given of a theoretical analysis of an adiabatic gas flow in a plane-parallel channel near the critical point. It is shown that the velocity profile ahead of the critical point must fill out, and that the mean velocity at the critical section exceeds the velocity of sound.     

Magnetic flow of viscous gas between rotating surfaces of revolution

In this work the steady laminar magnetic flow of viscous gas is considered in a narrow space (slot) between two surfaces of revolution rotating with constant angular velocities around a common axis of symmetry. The linearised equations of magnetic motion of the viscous gas flow for axial symmetry in the intrinsic curvilinear orthogonal coordinate system $\text{x, φ, y}$ are used. The obtained solutions of the equations of motion have been illustrated by examples of gas flow through the slot of constant thickness between rotating and fixed conical surfaces, and between rotating and fixed spherical surfaces.     

Numerical simulation of the gas flow in a circuit-breaker

A computational methodology for the solution of unsteady two-dimensional/axisymmetric Euler equations within geometries with moving boundaries is presented. The flow simulation is carried out by applying a finite-volume method which makes use of a Lagrangian-Eulerian version of Roe's approximate Riemann solver. The domain discretization is handled via unstructured triangular grids. Grid adaptation is applied on the basis of geometric and physical requirements. The importance of the implicit treatment of the space conservation laws, based on geometric analysis, is evoked. The procedure for reconstructing Roe's method for moving meshes is described and validated. Finally, the ability of the method for the prediction of the transient flow in a circuit-breaker during its opening phase is illustrated.     

Hypersonic flow of a viscous radiating gas over blunted cones

Employing the equations describing the dynamics of a viscous radiating gas, we examine the hypersonic flow over blunted cones under conditions of re-entry into the earth's atmosphere. The problem is solved by means of numerical methods.     

CFD simulation and optimization of the flow field in horizontal turbo air classifiers

This paper mainly presents a numerical study of the gas flow in horizontal turbo air classifiers. The effect of the air-inlet direction on the performance of classifier was also investigated through powder classification experiments. The simulated results show that the vertical vortex is the dominant flow in conical part of the classifier and there exists the horizontal vortex in the classifying chamber. The tangential velocity profile resembles a Rankine vortex inside the rotor cage. The vertical vortex intensity increases with increasing the inlet air velocity, while the rotor cage speed has limited effect on the control of gas pathlines in the classifying chamber. Horizontal turbo air classifiers are divided into four quadrants according to the air-inlet direction. For classifiers in quadrants I and III, a double-layer flow with opposite directions generates around the rotor cage which causes a secondary vortex. The secondary vortex is eliminated and the airflow becomes uniform in the classifier that belongs to quadrant Π or IV. The experimental results with fluidized catalytic cracking catalysts and fly ash demonstrate that cut sizes of this classifier decrease averagely by 5 μm and 2.2 μm respectively, and the classification accuracy increases by 7.5–10.3%.     

Numerical simulation of unsteady viscous flow around a circular cylinder

A finite difference solution is obtained for the time-dependent viscous incompressible 2-dimensional flow past a circular cylinder by direct integration of the Navier-Stokes equations expressed in a general curvilinear coordinate system. The solution describes the development of the vortex street developed behind the cylinder. Evolution of flow configuration is studied by means of streamlines, pressure contours, and vorticity contours for different Reynolds numbers. The time-dependent lift and drag coefficients are also obtained.     

工业超声波燃气表内部结构设计的气体流动仿真研究

利用流体动力学仿真软件CFX对新设计的G10超声波燃气表腔体结构的气体流动进行仿真研究和分析。在大、中、小流量点上分别仿真新设计结构内的气体流动,获得超声波燃气表的整个腔体内、腔体的YZ轴向截面上、XZ轴向截面上和XY轴向截面上的气体流速分布,并进一步获得3个截面上属于超声波测量的内流道部分的气体流速分布。对仿真结果进一步分析发现,与整个腔体气体流动和整个轴向截面上气体流动相比,超声波测量部分截面内气体流动更快,但相对更均匀和稳定,有利于超声波气体流速的准确测量。最后给出基于该设计结构的超声波燃气表样机的检测结果,检测结果也验证了用仿真来辅助表体结构设计的可行性。     

Control of flow past a body of revolution, minimizing the body’s drag in a viscous fluid

The problem of determination of the parameters and shape of a running wave on the surface of a body of revolution, which minimize the body’s drag, has been solved. The physical effects occurring in such a control have been analyzed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 5, pp. 109–111, September–October, 2006.