对组合机床加工流量计体产生缺陷问题的分析与解决

对镗铣组合自动机床加工流量计体中产生缺陷问题的分析,提出解决缺陷的办法.通过对镗铣专用机床加工流量计体过程中产生的分度误差、传动误差,以及铣削、镗削产生误差的原因进行分析,采用调整装刀高度,刃磨刀具和调整机床间隙等方法来消除加工缺陷,达到准确、稳定、高效的加工目的.另外,通过刃磨刀具提高刀具的利用率,节约刀具材料,降低制造成本.同时,避免因刀具在加工过程中出现撞击和振动,保证设备精度,延长设备使用寿命.该问题的解决办法已在实际应用中得到了验证,并广泛应用在加油机流量计生产过程中.

差压式流量计(壳体)制造与监督检验要点

目前差压式流量计(壳体)有制造监督检验要求,但尚无相应的制造与验收规范,造成制造企业对涉及壳体本质安全的质量把控不一,也给制造监督检验工作带来一定难度。本文结合差压式流量计(壳体)生产现状并结合制造监督检验要求,阐述并分析与差压式流量计(壳体)产品质量息息相关的设计、材料、焊接、检测、热处理与耐压试验等环节,希望能够给相关制造企业和监督检验人员带来参考,提升产品质量,促进行业进步。

双钝体涡街流量计的设计与研究

通过建立双钝体涡街流量计的物理模型和数学模型,应用基于有限体积法的Fluent软件对双钝体的流动现象进行了仿真研究。研究结果表明,通过双钝体诱发卡门涡街可以增强涡街强度,提高涡街流量计的信噪比,从而达到降低涡街流量计下限的目的。

双钝体涡街流量计的研究

通过仿真和用 5 0mm直径卡曼涡街流量计进行实验验证 ,得出 :双钝体组合能够增强流体振动 ,并且在钝体的轴对称点上存在相位相差 180°的流体振动点。采用双钝体组合结构和差动传感技术 ,能够研制出抗干扰性能良好和高灵敏度的新型涡街流量计。

双钝体涡街流量计钝体组合的试验研究

研究了不同组合双钝体的仪表系数—流量关系,通过压力损失分析,得到线性度及压力损失皆佳的一组钝体组合.给出了多种钝体组合结构的仪表系数及压力损失试验结果,表明双钝体结构在一定的流量范围内具有类似单钝体的常定斯特劳哈尔数.

内藏式锥体流量计的研制与应用

简述了大管径、节能、抗污内藏式锥体流量计的测量原理、结构特点及功能,以及用低速大型风洞实验设备进行流量计标定的实验方法和实验的结果。最后探讨了相关流计在工程使用中急需解决的问题和解决方法。

一种喷嘴式流量计壳体改进结构

当前,电站锅炉范围内管道上使用的流量计壳体常采用带有环焊缝焊接的结构,这种结构的环焊缝无法进行有效的内部无损检测,存在安全隐患。本文创新研究的喷嘴式流量计壳体改进结构,将壳体使用整段无缝钢管制成,既避免了焊缝存在的安全隐患,又简化制作工艺,从而实现了流量计制造的经济性和运行的安全性。

世界最小尺寸的气体质量流量计问世——新一代德尔塔巴气体质量流量计deltaflowC上市

万讯自控旗下再添品牌产品。日前新一代德尔塔巴气体质量流量计deltaflowC正式上市，这标志着世界上最小尺寸的气体质量流量计问世。据了解，该产品应用领域广，如压缩空气、空调系统、预热器中的空气、干峄空气、过程气体等。

在用化工管道流量计安全状况分析

化工行业管道输送介质用流量计型式种类繁多,结构多样。流量计(壳体)同样承载着化工管道对输送介质的作用,具有与压力管道相同的潜在危险性和事故危害性。但对其相应的规范要求非常有限,制造标准不完善,在企业管理、产品设计、材料使用、制造工艺、检验检测、安装使用各个方面都没有明确有效的规定,这使得整个流量计(壳体)制造行业都处于监管盲区的危险境地。文章对流量计(壳体)的制造监管、安装、使用检验等方面提出了建议。

煤化工粗煤气流量计的应用与改造

流量仪表是现代生产过程中计量重要的手段,同时它也是保证产品质量,安全生产和平稳运行的重要途径,随着智能化的产业不断发展,各个企业对其计量要求也是越来越高,没有一套完整的体系难以生存。当下对高压插入式涡街流量计的使用在逐步扩大。文章以煤化工企业为研究,对其计量仪表更新问题作了如下的阐述,结合现场实际工况,叙述了中煤鄂尔多斯能源化工有限公司变换装置入口粗煤气流量计应用过程中所存在问题及改进办法,成功解决了影响装置流量计量的问题。

流量计阀体精铸工艺设计

针对流量计阀体熔模铸件要求内部组织致密、流道尺寸精度高、流道表面粗糙度低等,采用ProCAST软件对其凝固过程进行数值模拟,优化组树工艺,保证铸件内部品质。采用水溶蜡芯配合制壳中封填砂工艺,保证流道尺寸及表面品质,从而得到优质铸件,缩短开发周期,降低试制成本。

Study on hydrodynamic vibration in fluidic flowmeter

The characteristics of the fluidic flowmeter,which is a combination of impinged concave wall and bistable fluid amplifier,is investigated by experimental studies and numerical simulations. The numerical approaches are utilized to examine the time dependent flow field and pressure field inside the proposed flowmeter. The effect of varying structural parameters on flow characteristics of the proposed fluidic flowmeter is investigated by computational simulations for the optimization. Both the simulation and experimental results disclose that the hydrodynamic vibration,with the same intensity,frequency and 180° phase shift,occurs at axisymmetric points in the feedback channel of the fluidic flowmeter. Using the structural combination of impinged concave wall and bistable fluid amplifier and differential signal processing technique,a novel fluidic flowmeter with excellent immunity and improved sensibility is developed.

Passive simulation method of turbine flow sensors based on the 6-DOF model

A passive simulation method based on the six degrees of freedom(6-DOF)model and dynamic mesh is proposed according to the working principle to study the dynamic characteristics of the turbine flow sensors.This simulation method controls the six degrees of freedom of the impeller using the user-defined functions(UDF)program so that it can only rotate under the impact of fluid.The impeller speed can be calculated in real-time,and the inlet speed can be set with time to obtain the dynamic performance of the turbine flow sensors.Based on this simulation method,three turbine flow sensors with different diameters were simulated,and the reliability of the simulation method was verified by both steady-state and unsteady-state experiments.The results show that the trend of meter factor with flow rate acquired from the simulation is close to the experimental results.The deviation between the simulation and experiment results is low,with a maximum deviation of 2.88%.In the unsteady simulation study,the impeller speed changed with the inlet velocity of the turbine flow sensor,showing good tracking performance.The passive simulation method can be used to predict the dynamic performance of the turbine flow sensor.

Influence of bluff body shape on wall pressure distribution in vortex flowmeter

To investigate the influence of bluff body shape on wall pressure distribution in a vortex flowmeter,experiments were conducted on a specially designed test section in a closed water rig at Reynolds numbers of 6.2×10 4-9.3×10 4.The cross sections of the bluff bodies were semicircular,square,and triangular shaped,and there were totally 21 pressure tappings along the conduit to acquire the wall pressures.It is found that the variation trends of wall pressures are basically identical regardless of the bluff body shapes.The wall pressures begin to diverge from 0.3D(D is the inner diameter of the vortex flowmeter) in front of the bluff body due to the diversity in shape,and all reach the minimum values at 0.3D behind the bluff body.A discrepancy between the triangular or square cylinder and the semicircular cylinder in wall pressure change is observed at 0-0.1D behind the bluff body.It is also found that the wall pressures and irrecoverable pressure loss coefficients increase with flow rates,and the triangular cylinder causes the smallest irrecoverable pressure loss at a fixed flow rate.

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.

Computational Simulation to Predict the Syngas Composition Produced during Charcoal Gasification

Charcoal gasification could mitigate the energetic problems in the rural zones since these regions have considerable amounts of wood, which is the base of such a fuel available. This paper presents some CFD （computational fluid dynamic） predictions of the experimental results obtained from the fixed bed gasification of charcoal made in a pilot-scale downdraft reactor using air, which was designed and built by the Research Group in Clean Development Mechanisms and Energy Management, from the National University of Colombia. The quality of the syngas obtained from the process was evaluated through the CO and CO2 percentages measured in its composition. The performance at various air flow rates （measured at the system entrance, through an analog flow meter） is evaluated with the help of 11 thermocouples, which give the information to create a temperature profile, and three load cells to measure the solid fuel conversion rate. To simulate the process, the information from temperature profile, charcoal proximate analysis, air flow meter and load cells were taken as inputs and the syngas composition was obtained as the result from the calculation. The domain was defined as 2D with an axis-symmetric description, using quads as mesh elements. The calculation and results were performed in a CFD commercial code widely used for this type of simulations： ANSYS FLUENT. The predictions made by the software were validated with the experimental results obtained in the laboratory.

Micromixing Efficiency of Viscous Media in Micro-channel Reactor

Micromixing efficiency of viscous media in Y-type micro-channel reactor was studied by using iodide-iodate test reaction as working system.Experiments were carried out in water-glycerin mixtures with 7 different viscosities.The experimental results showed that segregation index of the micro-channel reactor increases with the decrease of volumetric flow rate and the increase of solution viscosity.Based on the incorporation model,the micromixing time tm of the micro-channel reactor was estimated in the range of 10-4-10-3s at different viscosities,which indicated that the micro-channel reactor possesses a much better micromixing performance compared to the stirred tank(tm=0.02-0.2s).

CFD Prediction of Mean Flow Field and Impeller Capacity for Pitched Blade Turbine

This work focused on exploring a computational fluid dynamics(CFD)method to predict the macromixing characteristics including the mean flow field and impeller capacity for a 45° down-pumping pitched blade turbine(PBT)in stirred tanks. Firstly, the three typical mean flow fields were investigated by virtue of three components of liquid velocity. Then the effects of impeller diameter(D)and off-bottom clearance(C)on both the mean flow field and three global macro-mixing parameters concerning impeller capacity were studied in detail. The changes of flow patterns with increasing C/D were predicted from these effects. The simulation results are consistent with the experimental results in published literature.

Volume Estimation of Small Scale Debris Flows Based on Observations of Topographic Changes Using Airborne LiDAR DEMs

This paper describes a geographic information system(GIS)-based method for observing changes in topography caused by the initiation, transport, and deposition of debris flows using highresolution light detection and ranging(LiDAR) digital elevation models(DEMs) obtained before and after the debris flow events. The paper also describes a method for estimating the volume of debris flows using the differences between the LiDAR DEMs. The relative and absolute positioning accuracies of the LiDAR DEMs were evaluated using a real-time precise global navigation satellite system(GNSS) positioning method. In addition, longitudinal and cross-sectional profiles of the study area were constructed to determine the topographic changes caused by the debris flows. The volume of the debris flows was estimated based on the difference between the LiDAR DEMs. The accuracies of the relative and absolute positioning of the two LiDAR DEMs were determined to be ±10 cm and ±11 cm RMSE, respectively, which demonstrates the efficiency of the method for determining topographic changes at an scale equivalent to that of field investigations. Based on the topographic changes, the volume of the debris flows in the study area was estimated to be 3747 m3, which is comparable with the volume estimated based on the data from field investigations.

Experimental and CFD Study on the Role of Fluid Flow Pattern on Membrane Permeate Flux

This paper reports a study on the role of fluid flow pattern and dynamic pressure on the permeate flux through a micro filtration membrane in laboratory scale.For this purpose,a dead-end membrane cell equipped with a marine type impeller was used.The impeller was set to rotate in the clockwise and counter clockwise directions with the same angular velocities in order to illustrate the effect of rotation direction on permeate flux.Consequently, permeate fluxes were measured at various impeller rotational speeds.The computational fluid dynamics（CFD）predicted dynamic pressure was related to the fluxes obtained in the experiments.Using the CFD modeling,it is proven that the change in dynamic pressure upon the membrane surface has direct effect on the permeate flux.