外文翻译---基于内流场的数值模拟的磁力驱动泵在不同转速下的性能研究.docxVIP

英文原文Performance Study Based on Inner Flow Field Numerical Simulationof Magnetic Drive Pumps with Different Rotate SpeedsAbstract: Magnetic drive pump has gotten great achievement and has been widely used in some special fields. Currently, the researcheson magnetic drive pump have focused on hydraulic design, bearing, axial force in China, and a new magnetic drive pump with low flowand high head have been developed overseas. However, low efficiency and large size are the common disadvantages for the magneticdrive pump. In order to study the performance of high-speed magnetic drive pump, FLUENT was used to simulate the inner flow fieldof magnetic drive pumps with different rotate speeds, and get velocity and pressure distributions of inner flow field. According toanalysis the changes of velocity and pressure to ensure the stable operation of pump and avoid cavitation. Based on the analysis ofvelocity and pressure, this paper presents the pump efficiency of magnetic drive pumps with different rotated speeds by calculating thepower loss in impeller and volute, hydraulic loss, volumetric loss, mechanical loss and discussing the different reasons of power lossbetween the magnetic drive pumps with different rotated speeds. In addition, the magnetic drive pumps were tested in a closed testingsystem. Pressure sensors were set in inlet and outlet of magnetic drive pumps to get the pressure and the head。 The results of simulation and test were similar,which shows that the method of simulation is feasible. The proposed research provides the instruction to design high-speed magneticdrive pump.Key words: magnetic drive pump, simulation, power loss, pump efficiency.1.IntroductionMagnetic drive pumps are currently used in petrol andchemical industries to pump toxic, explosive, corrosive andexpensive fluid. High-speed magnetic drive pump will havean extensive prospect with the application of frequencyconversion technology and the requirement of environmental protection.Currently, studies on the design of magnetic drive pump,bearing, axial force and magnetic coupling have been goingon for several years, and some achievements have been got.Jiangsu University developed the magnetic drive pump withhigh power, which provided the design method of magnetic drive pump. Kong Fnayu developed a new bearing material FC5045, which is well in wearable performance and a new way to balance the axial force by using cooling cycle fluid which almost eliminate axial force6. Refs. 711 use ANSYS to simulate the efficiency of magnetic coupling, which improves the efficiency of magnetic drive pump. RIKKE, et al12, researched into the distribution of flow field by using large eddy simulation to simulate the inner flow field in impeller under different operating conditions.KITANO13 investigated into the distributions of pressure and velocity when impeller and pumping chamber were in different relative positions by simulating the unsteady flow in centrifugal pump. BENRA14 proved that the method of simulation was feasible by simulating velocity distribution in single-impeller centrifugal pump and comparing simulation with testing result of PIV. Many researchers have researched and analyzed inner flow field in the pump by using computational fluid dynamics(CFD). In order to do further research on the performance of magnetic drive pump, this paper presents the simulation of 3D turbulent model inside of magnetic drive pumps with different rotated speeds. The distributions of pressure and velocity in impeller and volute were got; head efficiency and power losses in normal-speed and high-speed magnetic drive pumps were discussed. The comparison of simulation with experiment showed that the method of simulation was feasible. In this paper, FLUENT is used to simulate the inner flow flied of magnetic drive pumps with different rotated speeds, and the velocity and pressure distributions of inner flow field and head are achieved. The pump efficiency is got by calculating the different power losses. Then magnetic drive pumps with different rotated speeds are tested, and the results show the method of simulation is feasible and provides instruction to design high-speed magnetic drive pump.2.Parameters and StructureThe design parameters are listed on Table 1 and thestructure is shown in Fig.1.3.Simulation of Inner Flow Field3.1 Control equationsThe fluid in magnetic drive pump is governed by physical conservation laws. It must meet mass conservation, momentum conversation and energy conservation. The flow in pump is supposed to be 3D, steady and incompressible. So continuity equation and N-S equation, according to Boussinesqs hypothesis, are expressed in Eq. (1):3.2 Turbulent modelThe standard k-e equations are applied in simulation of complex 3D turbulent. The equations are expressed in Eq. (2) 17:where sk, C, s, C1, and C2 are turbulent model coefficients, and the values, got from Launders recommended value and test result, respectively are 0.09,1.0, 1.3, 1.44, and Models and grid generationPro/Engineer was used to build 3D models of impeller and volute; Gambit was used to mesh the models with triangle mesh. The grids were checked and output. The models are shown in Fig. 2 and the number of grids is listed on Table 2.4.Simulation Results and Analysis Fig. 3(a) shows that in the normal-speed magnetic drive pump, the absolute velocity of fluid in the impeller increases with the growth of channel radius; the distribution of absolute velocity at the same circle is even; absolute velocity reaches the maximum at the outlet of the impeller; the absolute velocity of the fluid in the volute gradually decreases when fluid flows through the sections, and it reaches minimum at outlet of the volute. Fig. 3(b) shows that in the high-speed magnetic drive pump, the absolute velocity of fluid in the impeller increases with the growth of channel radius; the distribution of circumferential velocity becomes uneven, which causes vortex; the vortex makes the distribution of absolute velocity in the volute uneven; the vortexes between and section in high-speed magnetic drive pump are lager than those innormal-speed magnetic drive pump.Fig. 4(a) shows that in normal-speed magnetic drive pump, the relative velocity of fluid in impeller increases with the growth of impeller radius and it reaches the maximum at the outlet of the impeller; vortex appears at the end of the channel, which is quite intensive in volute tongue. Fig. 4(b) shows that in high-speed magnetic drive pump, the relative velocity of fluid in impeller increases with the growth of impeller radius; the axial vortex appears in vicinity of the inlet of impeller and it extends to the volute.The difference of relative velocities on suction surface and pressure surface in the channel causes the axial vortex. The vortex in high-speed magnetic drive pump is more intensive than that in normal-speed magnetic drive pump, because the difference of relative velocities in high-speed magnetic drive pump is larger than that in normal-speed magnetic drive pump.Fig. 5(a) shows that in normal-speed magnetic drive pump, the total pressure of fluid increases with the increment of impeller radius; it reaches the maximum at the outlet, and it keeps stabilizing after the fluid enters the volute. The distribution of total pressure in circumferential direction is even and the pressure on working face is slightly larger than that on back face. Fig. 5(b) shows that in high-speed magnetic drive pump, the total pressure of fluid becomes uneven in circumferential direction with the increment of impeller radius; high pressure appears in some areas; the pressure in the vicinity of working face and suction face is quite high and high pressure in the vicinity of volute tongue is very obvious; the distribution of total pressure is uneven because of vortexes and the difference of relative velocities; the pressure in the center of vortex is low, while it is rather high on the sides of vortex.Short blades can be applied in high-speed magnetic drive pump to decrease the width of channel so as to alleviate vortex; short blades should be equipped in the areas where vortex easily happens.Fig. 6 shows that static pressure distribution in the volute of high-speed magnetic drive pump is not as even as that in normal-speed magnetic drive pump; the high pressure appears in volute tongue in both of them; in high-speed magnetic drive pump, low static pressure appears in vortex, the areas of low static pressure enlarge fromsection to section, and the static pressure keeps stabilizing after section.Fig. 7 shows that total pressure distribution of vortex in high-speed magnetic drive pump is not as even as which in normal-speed magnetic drive pump; in normal-speed magnetic drive pump, high pressure appears between section andsection; in high-speed magnetic drive pump, the distribution of total pressure becomes even betweensection and section and low pressure areas appear behind section.5.Performance Analysis5.1 Hydraulic loss and hydraulic efficiency The head (H) is expressed in Eq. (4):5.2 Volumetric loss and volumetric efficiencyIn magnetic drive pump, a part of the fluid should be taken as cooling liquid circulation. Volumetric efficiency (v) is expressed in Eq. (7):where qFlow of cooling liquid circulation.5.3 Mechanical loss and mechanical efficiency5.3.1 Frictional loss In magnetic drive pump, frictional loss includes disc friction loss of shrouds of impeller and end face friction loss and surface friction loss of inner coupling. Friction loss (Pd) is expressed in Eq. (8):where MdFrictional torque of inner rotor (N m), w Angular speed of inner rotor (rad/s).5.3.2 Bearing power lossBearing power loss is expressed in Eq. (9):where PShaft power.5.4 Magnetic coupling efficiencyMagnetic coupling, instead of mechanical coupling, is applied in magnetic drive pump. Therefore, magnetic coupling efficiency (hc) must be considered in the calculation of pump efficiency.5.5 Pump efficiency When flow is 8 m3/h, head and efficiencies of normal-speed magnetic drive pump and high-speed magnetic drive pump calculated from the equations are shown in Table 3.The result shows that the inhomogeneity of distributions of flow field and vortex in high-speed magnetic drive pump is stronger than these in normal-speed magnetic drive pump. The hydraulic efficiency of high-speed magnetic drive pump calculated by simulation is 86%, while it is 81% for the normal-speed magnetic drive pump. Therefore, pump efficiency can be improved by increasing the speed which can allow a small impeller radius, and a small impeller can decrease disc friction loss and flow loss in the volute. For the low specific speed centrifugal pump, disc friction loss is the largest power loss among all power losses in the pump, and it will drastically decrease by reducing the impeller radius because disc friction loss is proportional to 5th power of impellers outside radius; hydraulic loss is only a little part of total loss, so the increment of hydraulic loss is less than the decrement of disc friction loss. So pump efficiency is improved. Table 3 shows that pump efficiency and impeller efficiency are quite low when the flow is small, and motor input power is mainly consumed in the impeller. When the flow increases, impeller efficiency increases, but disc friction loss, leakage loss and volute loss also increase.6 Test and Comparison6.1 Test resultsPerformance curves of CJRB8-70 and GCB8-70 areshown in Fig. 8 and Fig. 9.6.2 Comparison6.2.1 Head comparisonFig. 10 shows that simulating results accord with testingresults. Head differences of CJRB8-70 and GCB8-70 at different flow points are shown on Table Efficiency comparisonFig. 11 shows that simulating results accord with testing results. Efficiency differences of CJRB8-70 and GCB8-70 at different flow points are shown on Table 5.7.Conclusions(1) In normal-speed magnetic drive pump, absolute velocity distribution of fluid in the channel of impeller is quite even; relative velocity causes vortex at the end of thechannel, which is quite intensive in vicinity of volute tongue; total pressure on working face is lightly larger thanthat on back face. (2) In high-speed magnetic drive pump, distribution of absolute velocity in circumferential direction is uneven,which causes vortex; relative velocity causes axial vortex in vicinity of the inlet of impeller, which extends to the volute; distribution of total pressure in circumferential direction is uneven, and high pressure appears in some areas; pressure of fluid at the end of the channel of impeller is low, while the pressure on working face and suction face is quite high and the high pressure in vicinity of volute tongue is very obvious. These are the reasons why cavitation easily happens in high-speed magnetic drive pump. (3) In centrifugal pump with low specific speed, disc friction loss is the largest power loss among all power losses. Disc friction loss is proportional to 5th power of impeller radius, so the decrement of radius will drastically lead to the decrement of disc friction loss. Therefore, the increment of speed can allow a small impeller radius and make sure less disc friction loss so as to improve pump efficiency. (4) Power losses in normal-speed magnetic drive pump and high-speed magnetic drive pump are calculated, and pump efficiency got from simulation is in accordance with test results. The simulation proves that the method to calculate head and unit efficiency is feasible and the result is quite accurate.中文译文基于内流场的数值模拟的磁力驱动泵在不同转速下的性能研究摘要：磁力驱动泵的研究已经取得了很大的成就，并已被广泛使用在一些特殊领域。目前，在中国该研究主要集中在水力设计、轴承、轴向力驱动，一种新研制的低流量和高水头磁力驱动泵在国外也有很好的发展。然而，低效率和大尺寸是磁驱动泵共同的缺点。为了研究高速磁力驱动泵的性能，FLUENT被用于模拟内部流场的不同旋转速度，并得到内部流场的速度和压力。通过分析速度和压力的变化，确保泵的稳定运行，避免气蚀。基于对速度和压力的分析，本论文通过计算叶轮和叶壳中的热量损失、水力损失、容积损失，机械损失来计算磁力泵在不同旋转速度时效率；讨论磁力泵在不同旋转速度时热量损失的原因。此外，对磁力驱动泵在完全封闭的环境中进行测试。设置在磁力驱动泵进口和出口的压力传感器被用于获得压力和水头。仿真和测试结果相似，这表明模拟方法是可行的。拟议的研究为设计高速磁驱动泵提供了一些参考。关键词：磁力驱动泵；模拟；功率损失；磁力驱动泵效率1引言磁力驱动泵目前使用于汽油和化工行业，用于输送有毒，易爆，腐蚀性和昂贵的流体。高速磁力驱动泵，将随着变频技术的应用和环保的要求有更加广阔的发展前景。目前，磁力驱动泵的设计研究轴承，轴向力和磁耦合已持续几年，且已获得了一些成果。江苏大学研制的高效率磁力驱动泵，为以后的研究提供了一些设计方法。香港Fnayu研发出一种新的轴承材料FC504-5，通过冷却循环的方式使这种材料有很好的耐磨性能且可以平衡轴向力，进而抵消掉轴向力。Refs.7-11通过使用ANSYS来模拟磁耦合效率，从而提高了磁力驱动泵的效率。RIKKE，等12，通过采用大涡模拟的研究来模拟叶轮内部流场在不同的操作条件下的流场分布研究。北野13通过模拟离心泵的不稳定的流量来研究到当叶轮和泵室在不同的相对位置时的压力和速度分布。BENRA14通过模拟单叶轮离心泵的周转速率分配以及与PIV测试结果的比较可证明仿真模拟的思路是可行。许多研究人员通过计算流体力学（CFD）来研究和分析泵内流场。为了更深一层次的研究磁力泵的性能，本论文采取3维湍流模型模拟磁力泵内部不同的转速。已经获得了叶轮和叶壳中压力和速度的分布；讨论了在正常速度和高速下水头的效率和热量损失。通过模拟与实验的比较表明，模拟方法是可行的。在本论文中，FLUENT用于模拟磁力驱动泵在不同旋转速率时的内部流场；以及内部流场的速度和压力的分布且取得了一些成绩。通过计算不同热量损失来获得泵的效率。进而测试得到磁力泵的不同旋转速率，结果表明模拟方法是可行的，它为设计高速磁力驱动泵提供了一些方法。2参数和结构设计参数和结构分别列于表1和图1：表1磁力驱动泵的参数图1 磁力驱动泵的结构1套管 2叶轮 3内部耦合 4隔离罩 5指导轴承 6外部耦合3内流场仿真3.1控制方程流体中的磁力驱动泵遵循物理守恒定律。它必须满足质量守恒，动量定律和节约能源。泵的流量应该是三维的，稳定且不可压缩的。因此，连续性方程和NS方程根据布西奈斯克的假设，表达式（1）；其中：3.2湍流模型标准方程适用于模拟复杂的三维湍流。方程表示式（2）：其中，和是湍流模型系数，从实验结果中得到的测试值分别为0.09，1.0，1.3，1.44和1.92。3.3模型及并网发电Pro / Engineer被用于构建叶轮和蜗壳的三维模型;Gambit被用于将模型与三角网格啮合在一起。网格进行了检查和输出。 模型如图2所示，栅格的数量列于表2。图2网磁力驱动泵领域4. 仿真结果及分析图3（a）显示，处于正常旋转速度的磁力驱动泵，流体在叶轮中的绝对速度随着渠道半径的增长而增长；甚至绝对速度分布在同一个周期内；在叶轮出口处绝度速度达到了最大值；当流体经过I-IX部分时，涡螺壳中流体的绝对速度逐渐降低，在涡螺壳的出口处流体的绝对速度达到最小。图3（b）所示处于高速旋转的磁力驱动泵，叶轮中流体的绝对速度随着通道半径的增加而增加；微分速度圆周的分布变的不均匀，从而导致涡旋；涡流的产生使得涡螺壳中绝对速度的分布变的不均匀；高速磁力泵中的I和VI部分中的涡流比那些处于正常速度的磁力泵更大。图3 绝对速度分布磁力驱动泵（MS-1）图4（a）显示，处于正常速度的磁力驱动泵，叶轮中流体的相对速度随着叶轮半径的增加而增加，并在叶轮出口处达到最大值；涡流出现在渠道的最后，这是蜗舌相当密集的地方。由图4（B）可知，在高速磁力驱动泵中，流体的相对速度随着叶轮半径的增加而增加；轴向旋涡出现在进叶轮的附近和并且延伸到蜗壳中。图4 相对速度的分布磁力驱动泵（MS-1）在通道的表面压力作用下，吸力面相对速度的差异引起轴向旋涡。高速磁力驱动泵比正常速度的磁力驱动泵的涡流为密集，因为高速磁力驱动泵的速度差大于正常速度的磁力驱动泵。图5（a）表明，正常高速磁力驱动泵，流体总压力随叶轮半径增加而递增，达到最大值，最终保持稳定后的液体进入蜗壳。总压力的方向分布呈环形，工作面的压力稍大背面。图5（b）表明，高速磁力驱动泵流体总压力在圆周方向上的不平衡，高压出现在一些叶轮半径的增量变化大的区域；在工作面附近的压力和吸力是相当高的，而且在附近的高压蜗舌非常明；总压力变化是因为涡流不平衡，相对速度也有差异，在漩涡中心的压力低，而漩涡两侧是相