基于OPC与组态技术的气体流量自动检定系统的设计

针对目前在流量计生产制造中大量需要对气体流量计进行检定,为使检定结果高效、精确,在建立气体流量模型基础上,设计了标准表法气体流量检定装置的系统结构与构造,利用MATLAB实现了流量控制策略运算及仿真调试,采用OPC技术在组态王和King ACT软件之间实现了气体流量校准系统的数据采集的自动处理、在线检定、实时曲线查询,保证了检定过程自动化和高效性。对实验数据进行误差和不确定度计算分析,结果符合工业要求。     

十字星形高压动态流量计特性分析

从十字星形高压动态流量计的工作原理出发,对十字星形高压动态流量计的瞬时流量测量误差特性进行分析和仿真,与普通齿轮流量传感器相比,十字星形高压动态流量计瞬时流量测量误差脉动频率是普通齿轮流量传感器的4倍,十字星形高压动态流量计瞬时流量测量误差是普通齿轮流量传感器的1/4。     

标准表法气体流量自动检定系统的设计与实现

针对利用原气体标准装置对气体流量计进行校准时效率相对比较低的现状,研制标准表法气体流量在线实时检定系统。在分析气体流量校准原理基础上,构建气体流量模型,设计标准表法气体流量检定系统结构,采用PLC进行气体稳流控制,采集标准表和待测表的数据,根据温度压力数值修正到标况下数值,在组态王环境下完成标准装置的检定。该系统具有自动采集各种数据、自动计算以及自动打印报表和储存数据等功能,实现校准过程自动化、高精度与高效性。通过对标准装置的测量误差和不确定度的分析,该系统达到了设计要求。     

基于PLC与组态技术的气体超声波流量计校准平台

针对气体超声波流量计校准装置成本高、精度低、检定效率差的事实,以喷嘴流量计为标准表研制气体超声波流量校准平台。在分析超声波传输原理与校准平台结构的基础上,以50 mm管径为待测表管道,采用空气负压气源,建立气体流量模型,进行气体流量稳定的PID仿真验证。采用PLC控制电动阀实现稳流,经温压补偿运算后上传至组态界面,在组态监控环境下比较标准表和待测表的流量值,完成校准平台的实流检定。对校准结果进行测量性能指标分析,该平台达到了设计要求。     

液体流量校准装置应用集成平台

液体流量计种类繁多,在液体流量计校准时,对流量计的接线方式、校准方式和数据处理等各有区别。为解决目前液体流量校准装置在信息化和智能化水平低的问题,为提高液体流量校准装置使用的决策准确性并降低员工培训难度,为提高液体流量校准装置数据自动化处理水平减少校准等待周期,设计了液体流量校准应用集成平台。通过建立基于Web的液体流量校准装置专家系统提高决策的准确性;通过Web方式提高平台访问的便捷性;同时还提供液体流量计校准相关规程和案例的学习与测试功能,以提高平台使用性。该应用集成平台现已集成了液体流量计校准业务相关的功能,提供开展工作的基础应用服务功能,能有效协助装置使用人员降低约40%的决策失误率和缩短约30%的等待周期。     

基于Labview平台的流量计测量过程技术的探讨

研究了应用流量计测量流量过程的数据采集、信号处理、标定及动态测试等技术，建立了基于Labview软件、采集卡及测试实验台的流量测试系统，实现了流量的自动、准确测量。并采用一种简单、有效的方法验证了椭圆流量计动态测量的局限性，为研发流体自动测试系统提供了有效的技术支持。     

高精度气体微流量计工作用容积的测量

作为气体微流量标准的高精度气体微流量计主要用于气体微流量的测量,其中工作用容积值为气体微流量计的主要工作参数之一,因此气体微流量的测量精度也取决于工作用容积值的测量精度。比较称重法及静态膨胀法两种容积测量方法的优缺点,并根据实际情况采用静态膨胀法测量高精度气体流量计工作用容积,得到工作用容积值,并对测量结果进行不确定度的评定。该测量方法具有可原位置测量、操作简单、测量精度高等优点,满足高精度气体微流量计的要求。     

一种液体流量计动态性能评估方法

本文介绍了利用管道动态特性进行液体非定常流量测量的方法,提出了将该方法应用于工业流量计动态性能评估的思想,并根据该思想设计了一套简单实用的流量计动态性能评估装置。     

热式气体质量流量计在工业生产中的应用

本文主要介绍了大管径插入式热式气体质量流量计的特点,工作原理及安装和使用。本文对大管径插入式热式气体质量流量与孔板式差压流量计的性能指标也作了详细的比较。     

新型流量计动态节流元件文丘里管的研究与优化

根据动态节流元件流量计的工作过程,在雷诺数保持不变时流动是稳定的,改变流量压降可测得流量计局部压力损失。基于 Fluent 软件,分析了文丘里管的结构参数对压降的影响,并根据供热系统的实际情况选择了一组元件匹配合理的文丘里管参数。流量计样机完成后,通过使用二进制流量校准平台测试动态的节流元件。根据试验结果,优化也能较好地满足实际流动的条件。     

基于AMESim的斜盘式轴向柱塞泵脉动特性分析

在分析斜盘式轴向柱塞泵工作原理的基础上,利用经典理论公式计算其脉动系数;利用仿真软件AMESim建立柱塞泵系统理论模型,通过仿真计算出脉动系数并与理论公式计算结果进行对比,验算AMESim仿真计算方法的正确性;考虑配流等实际条件建立柱塞泵系统的实际模型,通过仿真运算得出具有不同柱塞数的柱塞泵在不同工况下的流量脉动系数和压力脉动系数,为泵的应用提供有益的参考.     

The influence of the pressure formation at the tip of the melt delivery tube on tin powder size and gas/melt ratio in gas atomization method

The production of metal powder using gas atomization technique is a wide spread process for manufacturing a wide range of spherical metal powder alloys. Metal powder properties generally improve with smaller powder particle size. Close-coupled atomizers are of great interest and controlling their performance parameters is critical for metal powder producing industries. In this study a new designed close-coupled nozzle system was used to produce tin powder to investigate the effect of the protrusion length of the melt delivery tube on the pressure formation at the melt tip. Observed improvement in particle refinement cannot be directly attributed to an increase in atomizing pressures and gas kinetics. Results from this study indicated that the observed metal flow rate was not behaving as what was earlier assumed, namely that, deeper aspiration enhanced metal flow rate. The melt flow rate was reduced with increasing the atomizing gas pressure. So that gas to melt mass flow ratio was increased for the same protrusion length and this ratio increase caused the finer powder particle size.     

大方坯连铸结晶器水口优化模拟探究

为了研究不同浸入式水口类型对结晶器内流场流动的影响,以结晶器水口优化为出发点,利用物理模拟和数值模拟两种手段对断面280 mm×380 mm大方坯结晶器不同水口开展优化研究。本研究首先构建了一个1∶1结晶器水模拟试验装置,实现不同浸入式水口下的连铸流动模拟,利用PIV测量了不同水口下的结晶器截面流场,然后利用Fluent软件进一步研究了浸入式水口开孔角度、开孔数目、安装角度等参数变化对结晶器内流场以及液面波动的影响。物理模拟和数值模拟研究表明,开孔角度向上时,波动范围大于5 mm;开孔角度水平时,对窄面冲击速度过大,达到0.35 m/s;较双孔水口,四孔水口液面速度为0.22 m/s,小于卷渣临界速度值;水口安装角度改为对角线时,强化了内流场角部流动,整个流场流动更加稳定。     

Numerical and Experimental Investigation of Cold Spray Gas Dynamic Effects for Polymer Coating

Low melting temperature materials such as polymers are known to be difficult to deposit using traditional cold spray techniques. Computational fluid dynamics (CFD) models were created for various nozzle geometries and flow conditions. A schlieren optical system was used to visualize the density gradients and flow characteristics in the free jet impingement region. Based on the CFD models, it was determined that a diffuser placed into the carrier gas flow near the nozzle exit not only leads to lower particle impact velocity required for polymer deposition, but also provides for appropriate application of compression heating of the particles to produce the conditions necessary at impact for successful coating adhesion of these materials. Experiments subsequently confirmed the successful deposition of polyethylene powder onto a 7075-T6 aluminum substrate. Using air as the carrier gas, polyethylene particles of 53-75???m diameter and 0.94?g/cm³ density_, were cold spray deposited onto the aluminum substrate, with a critical impact velocity of 191?m/s. No apparent melting of the polymer particles was observed. Refinements to these concepts are currently under investigation and a patent disclosure for the idea is pending.     

The influence of nozzle design on HVOF exit gas velocity and coating microstructure

A simple device was constructed for determining a value for the average combustion gas velocity at the exit plane of a high-velocity oxyfuel gun. This device was used to measure the velocities of a standard factory-made barrel nozzle and a specially designed de Laval nozzle as a function of the fuel/oxygen ratio and the total mass flow rate. The Mach number of the de Laval nozzle was 1.42. The maximum combustion gas exit velocities determined for the standard and the de Laval nozzles were 1100 and 1550 m/s, respectively. The maximum velocity depends on the fuel/oxygen ratio but is independent of the total flow rate. The effect of increased combustion gas velocity on coating quality is demonstrated.     

考虑位姿及锥度影响的柱塞副泄漏流量分析

针对轴向柱塞泵中柱塞存在加工锥度及运行中存在倾斜的事实,在综合考虑这2种因素影响的前提下,构建柱塞副泄漏流量模型。基于构建的泄漏流量模型,对柱塞副的泄漏流量进行分析,得到排油区柱塞副的临界半径间隙及2种因素对泄漏流量的影响。结果表明2种因素对泄漏流量的影响显著,所得临界半径间隙可为柱塞副的设计及排油区内泄漏流量方向的确定提供参考。     

高速燃气喷涂枪用燃油雾化喷嘴结构参数优化

为开发出以航空煤油为燃料的新型高速燃气喷涂枪,需设计出高效的煤油雾化喷嘴.文中提出了一种双气流空气助力雾化喷嘴,并运用计算流体动力学（CFD）模拟技术计算了该喷嘴的气流场,分析了喷嘴主、辅气出口截面积比对雾化气流场分布的影响规律,发现主、辅气出口截面积比增大,气流的喷射锥角相应增大,最大速度减小.综合考虑喷射锥角和气流速度对雾化效果的影响,确定主、辅气出口截面积比在1.01~1.34范围内喷嘴雾化效果较好.利用高速摄像系统对优化喷嘴的喷雾形态进行了试验分析,发现拍摄到的喷雾形态和计算机模拟结果一致,具有良好的雾化效果.     

三通道激光熔覆同轴送粉喷嘴气体速度场试验

在激光熔覆过程中,三通道同轴送粉喷嘴是关键部件,它利用惰性气体将金属粉末稳定地输送到熔池,同时形成保护流场,隔绝周围的空气。喷嘴气体流场对粉末的汇聚和高温区域的保护具有显著的作用,直接影响粉末利用率、金属材料性能和零件的成形精度。为了研究喷嘴保护流场特性,文中采用粒子图像测速(PIV)技术结合数值模拟计算,对自研的三通道同轴送粉喷嘴气体速度场分布进行了试验和分析。结果表明,喷嘴中心、内环和外环三个通道出口的气流速度一致时,喷嘴所形成的流场较为稳定,没有涡流存在。因此,粉末的汇聚性及对溶池的保护效果好;当外通道气流速度大于内通道时,在工件表面上出现旋涡,流场呈不稳定状态;随喷嘴与工件表面距离增加,有效保护范围减小。     

Numerical Studies of the Application of Shock Tube Technology for Cold Gas Dynamic Spray Process

A new method for a combustion-free spraying is studied fundamentally by modeling and simulation in comparison with first experiments. The article focuses on the numerical simulation of the gas-particle nozzle flow, which is generated by the shock reflection at the end wall section of a shock tube. To study the physical fundamentals of this process, at present only a single shot operation is considered. The particles are injected downstream of the nozzle throat into a supersonic nozzle flow. The measurements of the particle velocity made by a laser Doppler anemometry (LDA) set up show that the maximum velocity amounts to 1220 m/s for stainless steel particles of 15 μm diameter. The CFD-Code (Fluent) is first verified by a comparison with available numerical and experimental data for gas and gas-particle flow fields in a long Laval-nozzle. The good agreement implied the great potential of the new dynamic process concept for cold-gas coating applications. Then the flow fields in the short Laval nozzle designed and realized by the Shock Wave Laboratory (SWL) are investigated. The gas flow for experimentally obtained stagnation conditions is simulated. The gas-particle flow without and with the influence of the particles on the gas flow is calculated by the Surface Engineering Institute (IOT) and compared with experiments. The influence of the injection parameters on the particle velocities is investigated, as well. This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain Montavon, Ed., ASM International, Materials Park, OH, 2007.