超临界流体萃取-硅胶柱收集联用提取蓬莪术中有效成分

采用超临界流体ＣＯ２萃取和硅胶柱收集在线联用，提取蓬莪术中的挥发油，随后分别用正己烷、乙醇和乙醚对硅胶柱进行选择性洗脱，从而使蓬莪术挥发油中有效成分莪术二酮的相对含量由原来单一萃取的１０．７％提高到３４．７％。

基于DQM的空间轴对称流体饱和多孔热弹性柱体动力学特性研究

在热局部平衡条件下研究了空间轴对称不可压流体饱和多孔热弹性柱体在表面温度载荷作用下的动力学特性。基于de Boer多孔介质混合物理论,给出了问题的数学模型;其次综合采用微分求积方法-二阶向后差分法-Newton-Raphson迭代法求解了数学模型,得到柱体各离散点处未知物理量的数值结果,进而可分析柱体的动力学特性。为了验证该方法的正确性,计算了不可压流体饱和多孔弹性柱体的动力固结问题,并与de Boer等的解析结果进行了比较,两者吻合良好,也证明DQM有较小的计算量和较高的精度。最后分别研究和比较了柱体只受到表面外载荷作用下的动力学特性和受到两种表面温度载荷与外载荷联合作用下的动力学特性,考察了材料的某些参数对柱体动力学特性的影响。

呋喃酮和酱油酮的填充柱超临界流体色谱对映体拆分

采用填充柱超临界流体色谱对外消旋呋喃酮和酱油酮进行手性拆分。首先在分析型条件下,考察手性柱种类、改性剂种类和含量、柱温、柱压、流速等参数对容量因子、选择性因子、分离度的影响,获得拆分呋喃酮的较佳条件为手性柱Chiralpak AD-H、柱温30℃、柱压10MPa、改性剂1.0%(V/V)甲醇、流速1.5mL/min,得到分离度1.54;拆分酱油酮的较佳条件为手性柱Chiralpak AD-H、柱温33℃、柱压13MPa、改性剂1.5%(V/V)乙醇、流速1.5mL/min,得到分离度1.51。利用较佳条件进行制备规模放大,获得呋喃酮和酱油酮的对映体产品,光学纯度(对映体过量,e.e,%)均≥90%,回收率≥70%。对映体产品的获得可为探讨手性呋喃酮和酱油酮应用于食品加香的可行性提供基础条件。

地震资料中柱状流体运移通道形态参数及其地质意义

深部流体在向上运移的过程中,能够形成垂直-近似垂直的柱状通道,如气烟囱构造、流体逸散管道等。利用高分辨率地震资料,能够直观地对这些柱状地球物理异常进行精细的描述与刻画,从而统计其形态参数。综合不同海域的研究成果,本次研究系统总结归纳了柱状流体运移通道的8个重要参数,分别是发育层位、终止层位、平面形状、直径、高度和宽高比、反射偏移、椭圆率、拟合椭圆方位角。形态参数分别与通道群在平面上的展布方位、特殊的海底异常地貌(如海底麻坑、丘状体等)、深部构造发育与分布(如底辟、断层等)等进行耦合关联,能够进一步揭示柱状流体运移通道的地质含义。可将形态参数分为:(1)从形态学上对柱状通道进行直接分类的参数;(2)指示柱状通道形成诱发因素或形成过程的参数;(3)划分柱状通道幕式流体活动及期次的参数;(4)定义柱状通道中流体活动时间区间的参数;(5)间接反映柱状通道中流体通量相对大小的参数。实际研究过程中,单一形态参数难以准确反映出复杂地质背景下柱状通道的真实地质含义,多参数组合、相互对比验证,能够更好地对柱状流体通道的地质含义做出综合分析。

填充柱超临界流体色谱手性拆分5-羟基-8-十一碳烯酸-δ-内酯(茉莉内酯)

研究了填充柱超临界CO2流体色谱手性拆分外消旋5-羟基-8-十一碳烯酸-δ-内酯(茉莉内酯)的方法。在筛选固定相种类及改性剂种类基础上,通过单因素及正交实验较为系统地考察了柱温、柱压、改性剂含量、流速等因素的影响,优化出较佳的分析型拆分条件:固定相Chiralcel OD-H,柱温31℃,柱压12 MPa,改性剂为乙腈-甲醇(体积比7∶3),在流动相中体积分数2.0%,流动相流速1.0 mL/min,分离度2.00。利用较佳条件,在流速8mL/min下进行制备规模放大,320 min内进样10 mg得6.6 mg两对映体产品,回收率66%,光学纯度(e.e%)均为100%,表明超临界流体色谱分离效率高,可作为茉莉内酯mg级对映体纯品快速制备的手段。

基于渗透注浆原理的非正规垃圾填埋场防渗技术研究

针对非正规垃圾填埋场性质复杂、垃圾填埋不均一、污染源埋深大、容易造成地下水污染等特点,基于宾汉姆流体的柱—半球形扩散理论,进行了水平静压注浆防渗技术研究。通过改进注浆工艺、优化注浆流程,修复含水层隔水顶板,封堵污染因子向下迁移通道,保护地下水源。将该技术应用于河南省某非正规垃圾填埋场地下水污染治理,注浆后防渗层渗透系数为1.04×10^(-6)~3.81×10^(-5) cm/s,达到或高于粉质黏土的渗透级别,注浆段视电阻率显著降低,取得良好防渗效果,据此探索出一种阻隔高风险污染源与其下伏含水层的工程控制模式。

3-甲基-γ-辛内酯超临界流体色谱立体异构性制备拆分

用填充柱超临界流体色谱制备性拆分香料3-甲基-γ-辛内酯4个光学立体异构体。3-甲基-γ-辛内酯(合成的)首先在硅胶柱上制备拆分得其cis-、trans-异构体。然后,在分析模式下,考察手性柱种类、改性剂种类、改性剂含量、柱温、柱压的影响,获得拆分cis-、trans-异构体的较佳超临界流体色谱条件,cis-异构体:手性柱Chiralpak AD-H,柱温30℃,柱压9 MPa,改性剂甲醇体积分数4.0%,流动相流速1.5 mL/min,分离度1.45;trans-异构体:手性柱Chiralpak AD-H,柱温30℃,柱压10 MPa,改性剂甲醇体积分数4.5%,分离度2.24。在较佳的条件下对cis-、trans-异构体进行制备规模手性拆分得mg级4个光学立体异构体产品,光学纯度(对映体过量e.e)均为100%。

pSFC色谱法分离夏天无中的原阿片碱和延胡索乙素

目的建立一种采用色谱柱串联的填充柱超临界流体色谱法(pSFC)分离夏天无中原阿片碱和延胡索乙素,为生物碱类化合物的分离、制备提供新的方法。方法考察单用2-乙基吡啶柱(Pyr)时,改性剂比例、压力及温度对分离的影响。再将Pyr柱分别与二醇柱(Diol)、氰基柱(Cyano)串联。结果采用Pyr柱与Cyano柱串联,夏天无中原阿片碱和延胡索乙素能较好地分离。结论色谱柱串联运用于pSFC分离中药成分特别是生物碱,具有良好的应用前景。

Numerical Study of Pinching Liquid Filament Using VOF Method

Study on pinching liquid nlament in literature was reviewed. The breakup of liquid filaments under surface tension is governed by incompressible, two-dimensional (2-D), Navier-Stokes Equations. Surface tension was expressed via a CSF (continuous surface force) modei that ensures robustness and accuracy. A new surface reconstruction scheme, alternative phase integration (API) scheme was proposed to solve the kinematic equation, and was compared with other three referential schemes. A general-purpose computer program has been developed for simulating transient, 2-D, incompressible fluid flows with free surface of complex topology. The transient behavior of breaking Newtonian liquid filaments under surface tension was simulated successfully using the developed program. The initial wave growth predicted using API-VOF (volume of fluid) scheme was in good agreement with Rayleigh's linear theory and one-dimensional (1-D) long-wave theory. Both long wave theory and two-dimensional (2-D) API-VOF modei on fine meshes show that as time goes on, these waves pinch off large droplets separated by smaller satellite ones that decrease in size with decreasing wavelength. Self-similar structure during the breakup was found using 1-D and 2-D models, and three breakups were predicted for a typical case. The criterion of filament breaking predicted by the 2-D modei is that the wavelength is longer than the circumference of a filament. The predicted sizes of main and satellite droplets were compared with published experimental measurements.

Fluid Flow Past a Circular Cylinder with Tandem Rod and Staggered Rod at Low Reynolds Number

The flow past a primary cylinder with one tandem control rod and one staggered control rod is simulated in this paper through solving the Navier-Stokes equations. Two examples are simulated to validate the model, and the results matched well with those of previous researches. The Reynolds number based on the diameter of the primary cylinder is 500. The diameter ratio between the control rod and the primary cylinder （d/D） is 0.25. It was found that the effect of the combination of one upstream tandem control rod and one staggered control rod on the hydrodynamics of the primary cylinder is a linear superposition of the effect of a corresponding single control rod, and the effect of the upstream tandem control rod is dominant at larger spacing ratios such as G/D=2. For the combination of a downstream tandem control rod and a staggered control rod, the effect of the control rods is different from that of the corresponding single control rod in the region of 0.2〈G/D〈0.5 ＆ 30°〈a〈120° and 0.9〈G/D〈1.4 ＆ 30°〈a〈50°, where the additional effect is obvious. In this case, the effect of the downstream tandem control rod is dominant at small spacing ratios （such as G/D=0.1）. At moderate spacing ratios such as G/D=0.4, the effects of the tandem control rod and the staggered control rod are comparable in both cases.

Numerical investigation of laminar heat transfer and nanofluid flow between two porous horizontal concentric cylinders

In this study, the laminar heat transfer and nanofluid flow between two porous horizontal concentric cylinders was investigated. The problem is investigated in two different geometries and the Re=10, 25, 50, 75, 100 and volume fraction 0, 0.2%, 0.5%, 2% and 5% that related to copper nanoparticles, and porous medium porosity of 0.5 and 0.9. Compared to the first geometry, the convective coefficient in the second geometry increases by 8.3%, 7% and 5.5% at Reynolds numbers of 100, 75 and 50, respectively. Comparison of the outlet temperatures for two heat fluxes of 300 and 1200 W/m^2 indicates a 2.5% temperature growth by a fourfold increase in the heat fluxes. Also, the higher Nusselt number is associated with the second geometry occurring at porosities of 0.9 and 0.5, respectively. In both geometries, the Nusselt number values at the porosity of 0.9 are higher, which is due to the increased nanofluid convection at higher porosities. The velocity of the nanofluid experiences a two-fold increase at the outlet compared to its inlet velocity in the first geometry and for both porosities. Similarly, a three-fold increase was achieved in the second geometry and for both porosities.

Simulating the dynamics of fluid-cylinder interactions

We present the simulation of the dynamics of fluid-cylinder interactions in a narrow three-dimensional channel filled with a Newtonian fluid, using a Lagrange multiplier based fictitious domain methodology combined with a finite element method and an operator splitting technique. As expected, a settling truncated cylinder turns its broadside perpendicular to the main stream direction and the center of mass moves to the central axis of the channel. In the case of two truncated cylinders, they first move around each other for a while and then stay together in a "T" shape. After the "T" shape has been formed for a long enough time, we found no vortex shedding behind the cylinders. When simulating the fluidization of 60 truncated cylinders, we captured the features of interactions among fluidized cylinders as observed in experiments.

Some Magnetized Bulk Viscous String Cosmological Models in Cylindrically Symmetric Inhomogeneous Universe with Variable Λ-Term

Some cylindrically symmetric inhomogeneous viscous fluid string cosmological models with magnetic field and cosmological term A varying with time are investigated. To get the deterministic solution, it has been assumed that the expansion （θ） in the model is proportional to the eigen value σ^11 of the shear tensor σ^ij. The value of cosmological constant for the model is found to be small and positive, which is supported by the results from recent supernovae Ia observations. The effect of bulk viscosity is to produce a change in perfect fluid and hence exhibits essential influence on the character of the solution. The physical and geometric properties of the models are also discussed in presence and absence of magnetic field.

Numerical simulation of flow around square cylinder using different low-Reynolds number turbulence models

ABE-KONDOH-NAGANO,ABID,YANG-SHIH and LAUNDER-SHARMA low-Reynolds number turbulence models were applied to simulating unsteady turbulence flow around a square cylinder in different phases flow field and time-averaged unsteady flow field.Meanwhile,drag and lift coefficients of the four different low-Reynolds number turbulence models were analyzed.The simulated results of YANG-SHIH model are close to the large eddy simulation results and experimental results,and they are significantly better than those of ABE-KONDOH-NAGANO,ABID and LAUNDER-SHARMR models.The modification of the generation of turbulence kinetic energy is the key factor to a successful simulation for YANG-SHIH model,while the correction of the turbulence near the wall has minor influence on the simulation results.For ABE-KONDOH-NAGANO,ABID and LAUNDER-SHARMA models satisfactory simulation results cannot be obtained due to lack of the modification of the generation of turbulence kinetic energy.With the joint force of wall function and the turbulence models with the adoption of corrected swirl stream,flow around a square cylinder can be fully simulated with less grids by the near-wall.

Study on Hydrodynamic Vibration in Dual Bluff Body Vortex Flowmeter

The characteristics of the dual bluff body vortex shedding is investigated, and the possibility to use dual bluff body combinations to strengthen the hydrodynamic vibration around the bluff body objects is explored. The numerical and experimental approaches were utilized to examine the time dependent flow field and the pressure oscillation around the bluff bodies. The numerical data were obtained by the advanced large eddy simulation model. The experiment was conducted on a laboratory scale of Karman vortex flowmeter with 40 mm diameter. It is revealed that the optimized dual bluff body combinations strengthened the hydrodynamic vibration. It was also found that the hydrodynamic vibration with 180° phase difference occurred at the axisymmetric points of circular pipe on the lateral faces of the equilateral triangle-section bluff bodies. Using the dual bluff body configuration and the differential sensing technique, a novel prototype of vortex flowmeter with excellent noise immunity and improved sensibility was developed.

A single-phase turbulent flow numerical simulation of a cyclonic-static micro bubble flotation column

Improved fluid dynamics can enhance the separation efficiency of flotation methods. A Computational Fluid Dynamics simulation using FLUENT was performed to model the fluid environment of a cyclonic-sta- tic micro bubble flotation column. The simulation results visually show the interior flow and illustrate mix- ing of the different flows within the apparatus. An analysis of the distribution in velocity and vorticity was used to analyze the separation mechanism and the synergism of the component parts and to strengthen the design of each unit. The conclusions are that axial back mixing and vortexes still exist in the separation unit even in the presence of packing media. The inverted cone structure near the tangential inlet （cone 1 ） within the cyclonic unit is the main reason for this. The cone 1 structure enhances swirling and focuses energy within the inner area of the cone where there are abundant bubbles. As a result slowly floating minerals are forcibly recovered and railings are effectively separated within this unit. However, cone 1 also reduces the vorticity downstream from it, which reduces the efficiency of railings separation within this part. Therefore, the design of cone 1 should be based on the principles of lessening disturbances to the column unit while strengthening the separation effect of the cyclonic unit. Also, the axial distance between the paired cyclonic structures at the bottom of the column （cone 2） and cone 1 poses tough requirements because of an interaction between separation of the middlings and railings.

Local Flow Regime Transition Criteria of Gas-Liquid Two-phase Flow in Vertical Upward Tube with a Horizontal Rod

The upward multiphase cross flow and heat transfer in the vertical tube may occur in oil production and chemical facilities. In this study, the local flow patterns of an upward gas-water two phase cross flow in a vertical tube with a horizontal rod have been investigated with an optical probe and the digital high speed video system. The local flow patterns are defined as the bubble, slug, churn and annular flow patterns. Optical probe signals are ana- lyzed in terms of probability density function, and it is proved that the local flow patterns can be recognized by this method. The transition mechanisms between the different flow patterns have been analyzed and the corresponding transitional models are proposed. Finally, local flow pattern maps of the upward gas-water two-phase flow in the vertical tube with a horizontal rod are constructed.

3D hydrodynamics involving multiple eccentric impellers in unbaffled cylindrical tank

In this paper, the numerical predictions of 3D hydrodynamics and power consumption in a vessel stirred by mul- tiple eccentrically located impellers are presented. The vessel is a fiat-bottomed cylindrical one equipped with six-curved bladed impellers. Aqueous solutions of xanthan gum are used, which have a shear thinning behavior with yield stress. The influence of several parameters on the mixing efficiency has been investigated, namely： the stirring rate, fluid theology, impeller number and impeller clearance from the tank bottom. Our predicted results are compared with other experimental data and a satisfactory agreement is found.

Performance Investigation of 2D Lattice Boltzmann Simulation of Forces on a Circular Cylinder

The lattice Boltzmann method (LBM) is employed to simulate the uniform flow past a circular cylinder. The performance of the two-dimensional LBM model on the prediction of force coefficients and vortex shedding frequency is investigated. The local grid refinement technique and second-order boundary condition for curved walls are applied in the calculations. It is found that the calculated vortex shedding frequency, drag coefficient and lift coefficient are consistent with experimental results at Reynolds nu...

Vibration and Instability of Third⁃Order Shear Deformable FGM Sandwich Cylindrical Shells Conveying Fluid

The vibration and instability of functionally graded material(FGM)sandwich cylindrical shells conveying fluid are investigated.The Navier-Stokes relation is used to describe the fluid pressure acting on the FGM sandwich shells.Based on the third-order shear deformation shell theory,the governing equations of the system are derived by using the Hamilton’s principle.To check the validity of the present analysis,the results are compared with those in previous studies for the special cases.Results manifest that the natural frequency of the fluid-conveying FGM sandwich shells increases with the rise of the core-to-thickness ratio and power-law exponent,while decreases with the rise of fluid density,radius-to-thickness ratio and length-to-radius ratio.The fluid-conveying FGM sandwich shells lose stability when the non-dimensional flow velocity falls in 2.1-2.5,which should be avoided in engineering application.