EXTRACTION KINETICS OF RARE EARTH（Ⅰ） A Constant Interfacial Cell with Laminar Flow

A technique was developed to study mass trans fer process and inter facial reaction in two phases system. This constant inter facial cell with a laminar flow was made into a cubic structure. The two fluids were continuously recycled and mixed. The concentration of each liquid could be monitored by two different methods. This kind of structure made both flows near the inter face flow parallel to the inter face. The inter face was smooth and steady. The mass trans fer rate could be judged by the linear velocity of the flows. The technique can be used for the analyses of the control step in both phases near the inter face in a diffusion control process. A preliminary hydrodynamics and mass trans fer study on the cell was presented, which ensures the distinguishing between a diffusion and a chemical reaction control process. A simplified mass transfer equation,N =0.5303D 1 /2* (Ci- Cb)* (V / B) 1/2, was achieved.

Extraction Kinetics of Lanthanum in Chloride Medium by Bifunctional Ionic Liquid [A336][CA-12] Using a Constant Interfacial Cell with Laminar Flow

The extraction kinetics of La(III) from aqueous chloride solutions into n-heptane solutions of bifunctional ionic liquid extractant [A336][CA-12](tricaprylmethylammonium sec-octylphenoxy acetic acid) was investigated using a constant interfacial cell with laminar flow. The effects of stirring speed, temperature and specific interfacial area on the extraction rate were examined. The results indicate that mass transfer kinetics of La(III) is a mixed-controlled process influenced by interfacial reaction. On the basis of mass transfer kinetic results in the extraction of La(III) by [A336][CA-12], the extraction rate equation of La(III) is proposed in terms of pseudo-firstorder constants, which is supported by the measured thermodynamic equations. The mass-transfer kinetic model deduced from the rate controlling step is adequate to interpret the experimental data qualitatively.

基于Flowmaster软件的恒压泵系统流量调控的能耗分析

供水泵站通常采用阀门或变速(变频)调控来实现恒压供水,2种方式都涉及管路特性曲线或泵性能曲线的变化,这使得实际应用中能耗的定量计算比较繁琐.为此,借助Flowmaster流动系统仿真软件,以某恒压供水站为例,分别计算阀门调控和变速调控方式下泵系统性能的变化,并进行能耗对比分析,研究了恒压泵系统的转速和流量调节范围,为工程应用提供切实可行的计算方法.

EFFECT OF THE MAGNETIC FIELD ON THE PULSATILE FLOW THROUGH A RIGID TUBE

This study presents the effect of the magnetic field with constant intensity on the pulsatile flow through a rigid tube. Basing on the experimental results, the influence of the magnetic field on the blood viscosity is considered The analytic solution of the pulsatile flow through a rigid tube under constant magnetic field intensitier and the effect of the magnetic field on the velocity distribution, flow and impedance in a rigid tube are given. this investigation is valuable for understanding the influence of the magnetic field on the blood circulation.

Transient Pressure Behavior of a Well Located between a Constant Pressure Boundary and a Sealing Fault

Pressure transient analysis has been used to evaluate performance of a well located between one sealing fault and one constant pressure boundary. Type curves were generated by determining 1) dimensionless pressure and 2) rate of change of dimensionless pressure drop with respect to dimensionless time. When the well is located closer to the no flow boundary, both sets of type curves have three distinct slopes. These slopes characterize: 1) flow in an infinite reservoir, 2) presence of the no flow, and 3) the constant-pressure boundaries. When the well is closer to the constant pressure boundary, the type curves show two distinct slopes. These correspond to: 1) flow in an infinite reservoir, and 2) the presence of a constant pressure boundary. The type curves can be used to match actual pressure drawdown data and determine the drainage area and relative well location with respect to physical boundaries.

基于恒热流法和恒温法的岩土热物性试验分析研究

目前岩土热物性测试仪采用的方法包括两种:恒热流法和恒温法,通过介绍两种测试方法的区别及模型算法,以北京市某公建项目岩土热物性测试结果为基准,利用TRNSYS软件分别模拟了恒热流法和恒温法的测试工况,针对模拟结果展开分析研究。经对比,试验时间至48 h时,两种测试方法利用软件模拟出的延米换热量与现场测试结果的误差在10%以内,表明若已知项目周边的地层热物性参数如地层的导热系数、热扩散率等,可将软件模拟结果作为前期地埋管系统设计的依据,并作为后续热物性勘察结果验证的参考数据。此外,根据模拟结果,由于夏季地埋管流体在设计工况下与土壤的温差值较大,为了使流体尽快达到设计工况点,恒温法测试时应选用较大的功率,否则48 h内的测试值结果与实际值偏差较大。

Capillary Micro-flow Through a Fiber Bundle(Part 2)

A numerical model was proposed to simulate the capillary micro-flow through a fiber bundle. The capillary pressure was predicted by the Young-Laplace equation and the corresponding optimal values of permeability were found by a trial-and-error method. The empirical Kozeny constants which are dependent on fiber volume fraction were recormnended for the prediction of permeability.

ON THE EFFECT OF REYNOLDS NUMBER ON VON KRMN'S CONSTANT

Fully developed turbulence measurements in pipe flow were made in the Reynolds number ranging from 10 x 10~3 to 350 x 10~3 with a hot-wire anemometer and a Pitot tube.Comparisons were made with the experimental results of previous work.The mean velocity profile and the turbulent intensity in the experiments in- dicate that for the mean velocity profile,in the fully developed turbulent pipe flow, von Kármán's constant κ is a function of Reynolds number,i.e.κ increases slowly with the Reynolds number.The empirical relationships could not be considered to be accurate enough to describe the fully developed turbulence over the whole Reynolds number range in pipe flow.

An Adaptive Response Compensation Technique for the Constant-Current Hot-Wire Anemometer

An adaptive response compensation technique has been proposed to compensate for the response lag of the constant-current hot-wire anemometer (CCA) by taking advantage of digital signal processing technology. First, we have developed a simple response compensation scheme based on a precise theoretical expression for the frequency response of the CCA (Kaifuku et al. 2010, 2011), and verified its effectiveness experimentally for hot-wires of 5 μm, 10 μm and 20 μm in diameter. Then, another novel technique based on a two-sensor probe technique—originally developed for the response compensation of fine-wire thermocouples (Tagawa and Ohta 1997;Tagawa et al. 1998)—has been proposed for estimating thermal time-constants of hot-wires to realize the in-situ response compensation of the CCA. To demonstrate the usefulness of the CCA, we have applied the response compensation schemes to multipoint velocity measure- ment of a turbulent wake flow formed behind a circular cylinder by using a CCA probe consisting of 16 hot-wires, which were driven simultaneously by a very simple constant-current circuit. As a result, the proposed response compensation techniques for the CCA work quite successfully and are capable of improving the response speed of the CCA to obtain reliable measurements comparable to those by the commercially-available constant-temperature hot-wire anemometer (CTA).

基于恒流式热线风速仪的流速检测实训台设计

基于恒流式热线风速仪设计了可实现复杂表面的气流测量和湍流结构分析的流速检测实训台。实训台在基于单片机的硬件电路上创新设计,保证了较高的测量精度。可用于相关专业的教科研,同时也可用于学生自制热线式风速探针的校准,提高学生的动手操作能力,培养学生的学习兴趣。

New Mechanism and Analytical Formula for Understanding the Gravity Constant <i>G</i>

The nature of gravitation and G is not well understood. A new gravitation mechanism is proposed that explains the origin and essence of the gravitational constant, G. Based on general relativity, the vacuum is considered to be a superfluid with measurable density. Rotating bodies drag vacuum and create a vortex with gradient pressure. The drag force of vacuum fluid flow in the arm of the vortex is calculated relative to the static vacuum and a value that is numerically equal to that of G is obtained. Using Archimedes’ principle, it is determined that G is the volume of vacuum displaced by a force equivalent to its weight which is equal to the drag force of the vacuum. It is concluded that the gravitational constant G expresses the force needed to displace a cubic metre of vacuum that weighs one kg in one second. Therefore, G is not a fundamental physical constant but rather is an expression of the resistance encountered by the gravitational force in the vacuum.

Unsteady Spillway Flows by Singular Integral Operators Method

The Singular Integral Operators Method (S.I.O.M.) is applied to the determination of the free-surface profile of an un-steady flow over a spillway, which defines a classical hydraulics problem in open channel flow. Thus, with a known flow rate Q, then the velocities and the elevations are computed on the free surface of the spillway flow. For the numerical evaluation of the singular integral equations both constant and linear elements are used. An application is finally given to the determination of the free-surface profile of a special spillway and comparing the numerical results with corresponding results by the Boundary Integral Equation Method (B.I.E.M.) and by using experiments.

Heat Transfer with Viscous Dissipation in Couette-Poiseuille Flow under Asymmetric Wall Heat Fluxes

Analytical solutions of temperature distributions and the Nusselt numbers in forced convection are reported for flow through infinitely long parallel plates, where the upper plate moves in the flow direction with constant velocity and the lower plate is kept stationary. The flow is assumed to be laminar, both hydro-dynamically and thermally fully developed, taking into account the effect of viscous dissipation of the flowing fluid. Both the plates being kept at specified and at different constant heat fluxes are considered as thermal boundary conditions. The solutions obtained from energy equation are in terms of Brinkman number, dimensionless velocity and heat flux ratio. These parameters greatly influence and give complete understanding on heat transfer rates that has potentials for designing and analyzing energy equipment and processes.

多水源地长距离供水工程恒定流水力仿真研究

本文基于压力管道水力学基本理论,针对长距离多泵站、多水源地供水联合运行问题,建立供水工程管网系统恒定流水力仿真模型,分别求解日常运行、常规检修与应急抢险等不同工况下管网系统中各点的压力与流量变化情况,从而检验系统的运行情况。结果表明,各工况下该供水系统压力极值都符合管道的承压标准,具备安全过流条件,可为类似供水工程的运行提供一定的参考作用。

恒定流作用下泥沙垂向相对暴露度试验研究

基于泥沙三维受力分析,探讨垂向相对暴露度对单颗粒泥沙起动的影响,推导考虑垂向相对暴露度影响的单颗粒泥沙起动流速公式。通过概化单颗粒泥沙起动试验测量数据,明确泥沙起动公式中的上举力系数与拖曳力系数。研究结果表明,上举力系数和拖曳力系数与水流条件和颗粒粒径有关,在恒定流作用下垂向相对暴露度增大导致拖曳力系数和上举力系数增大。当垂向相对暴露度到达一定数值后,拖曳力系数与上举力系数均有逐渐减小的趋势。相同泥沙粒径情况下,单颗粒泥沙起动流速随着垂向相对暴露度的增加而增加。垂向相对暴露度不仅改变单颗粒泥沙所受力臂大小,且改变了作用在单颗粒泥沙上的流速大小,影响了泥沙的起动。

基于功率恒定的防饱和在线取电方法

基于厄流线圈取电装置提出了一种防止铁磁磁心饱和的方法,该方法使用旁路泄流电路将流入电流互感器过多的电流引入到旁路电路中消耗掉,将输出功率作为反馈值来调节旁路电路中开关管的关断,通过控制输出的功率大小,输电线路在宽范围电流内实现恒功率输出和防止电流互感器磁心到达饱和。根据电流互感器各方面的要求,建立电流互感器3D模型,将3D模型导入到Maxwell中对电流互感器本身进行有限元仿真分析,得到电流互感器内部各项参数,再将经过有限元分析的电流互感器模型导入到ANSYS中与外部电路组成取电电路进行联合仿真,通过仿真结果验证电流互感器的取电能力。再加入本次对电流互感器取电优化部分,通过电流互感器二次侧谐振的方式增加一次侧输电线路的等效阻抗,考虑到电流互感器磁心饱和的问题,采用旁路泄流电路将过多的电流通过旁路绕过电流互感器一次侧回到输电线路当中的方法解决。

恒流径向柱塞泵输出特性分析与试验

基于特种装备车辆转向系统恒流量需求的背景,以优化某型恒流量径向柱塞泵输出动特性为目的,进行了恒流量机理解析及流量脉动分析优化。针对流量输出特性搭建了数学及仿真模型,并对比仿真、试验结果,以验证原理、模型的有效性。并以恒流量值、恒流量临界转速为约束条件,对流量脉动率进行了优化分析研究。结果表明:可通过该型结构实现柱塞泵恒流量功能;在输入转速大于恒流量临界转速后,随转速升高,平均流量将趋于稳定,而流量脉动将随转速升高而升高;通过优化柱塞直径、偏心距和节流口开口量,可有效降低流量脉动率5%以上。

电液伺服控制柱塞泵转速干扰及控制策略研究

为克服电机转速对电液伺服控制变量轴向柱塞泵输出特性产生的干扰问题,建立电液伺服控制轴向柱塞泵系统的Simulink-AMESim仿真模型,以恒流量为评价指标研究电机转速干扰条件下电液伺服控制变量柱塞泵恒流量控制的输出特性,分别利用传统PID及模糊自适应PID控制策略对电液伺服控制变量柱塞泵进行抗干扰控制,获得不同类型干扰情况下电液伺服控制变量泵系统的输出特性曲线。仿真结果表明:恒流量控制下,电液伺服控制变量柱塞泵的流量波动为3.80 L/min,当电机转速分别存在正弦波、方波及三角波脉冲扰动工况时,流量波动分别上升至9.34 L/min、9.59 L/min、4.52 L/min。分别利用PID及模糊自适应PID对电液伺服控制变量柱塞泵进行抗干扰控制,流量波动分别降低了3.41 L/min和5.90 L/min。

基于TRNSYS太阳能地源热泵供暖系统仿真研究

利用DEST建筑能耗模拟软件,对张家口市某建筑进行全年逐时热负荷模拟,利用太阳能和地热能两种可再生能源作为供暖热源,以TRNSYS建立太阳能地源热泵系统仿真模型,在供暖期采用定流量和变流量两种不同的系统运行方式进行模拟分析,分析结果表明,两种供暖系统COP分别为3.74和4.29。采用定流量方式运行时,循环水泵总能耗为9610.87kW/h,热泵机组总能耗为26122.69kW/h,系统总能耗为35733.56kW/h。负荷侧采取变流量方式运行时循环水泵总能耗为6229.89kW/h,热泵机组总能耗为24961.36kW/h,系统总能耗为31191.25kW/h。根据结果可看出,相对于定流量运行,用户侧变流量运行下系统COP提高14.7%,系统总能耗减少14.56%。负荷侧变流量运行下太阳能地源热泵系统整体性能更优。

基于P-V自动调节的活塞式气体流量装置研究

为研究超声波、热式燃气表在空气介质与天然气介质条件下的流量特性及差异,设计了一种基于压力-体积(P-V)自动调节的活塞式气体循环流量标准装置。介绍了装置基本架构、工作原理。分析了流体流动闭合回路中影响测量精度的原因。建立了实现定常流的P-V自动调节控制数学模型。该装置采用主动盘形活塞式流量标准器,体积扩展不确定度U r=0.07%;配置柱形活塞作为容积补偿,通过监测气体压力变化调节活塞运动方向及速度,以达到压力恒定的目的。装置配置了六表位工装台架,并设置最大工作压力为0.1 MPa、最大流量为10 m^(3)/h、量程比为1000∶1;通过测试六台G2.5超声波燃气表,得出压力波动小于5 Pa、流量稳定性优于0.02%。在流量测试领域,P-V自动调节方法可以为实现定常流提供新的解决思路。