微尺度射流流量计的设计与仿真研究

MEMS流量控制系统中,需要微型化的流量传感器,设计了一种反馈流驱动的微尺度射流流量计.采用数值模拟的方法对微尺度射流流量计进行研究,CFD软件的仿真结果表明:在较宽入口速度范围内该微尺度射流流量计起振快,振荡稳定,切换灵敏,斯特劳哈尔数基本恒定,并且流速测量下限可以达到0.075 m/s,在一定程度上为射流流量计的微...     

方向选择性流速传感器研制

该文提出具有方向选择性并通过热平衡检测流速的方法,隔热套管与流体接触面之间平行安装,并保持有一特殊距离,实现方向选择性,通过检测流体接触面的温度来测量流体流速。用这种方法研制了一种单方向流速测量传感器,扩展用于构成三维风速传感器。该传感器可广泛应用于风力发电、气象预报、空间飞行器、工业锅炉等领域的气体和液体速度场、流量场测量。     

一种基于温差测量原理工作的集成型流量传感器􀀂

在比较已有的几种低流速流体的流速流量测量方法基础上,提出一种利用与流速相关温差的测量方案,并用芯片集成方法构成流量传感器加以验证,实验结果与理论预期基本相符.该传感器的主要优点是在低流量条件下具有高灵敏度.     

大量程比射流流量计的仿真研究

本文在传统射流流量计的基础上,设计了新的振荡腔结构,目的在于拓宽新型射流流量计的量程比,提高其工作的适应性和稳定性.在计算流体软件FLUENT平台上进行数值仿真研究,通过对数据和图线的分析,获得了较大范围内流量和频率的线性关系以及此范围内基本恒定的斯特罗哈数.仿真结果表明,设计的新型射流流量计附壁稳定、切换可靠,测得的流量与振荡频率有着良好的线性关系,在较大范围内验证了Strouhal方程,在一定程度上能为射流流量计的设计提供依据.     

浅析涡街流量计旋涡发生体形状对稳定测量的影响

测量流体流量的仪表统称为流量计或流量表,流量计是工业测量中重要的仪表之一。随着工业生产的发展,对流量测量的准确度和范围的要求越来越高,流量测量技术日新月异。为了适应各种用途,各种类型的流量计相继问世,目前已投入使用的流量计已超过100种。流体振荡式流量计是利用流体在特定流道条件下流动时将产生振荡,且振荡的频率与流速成比例这一原理设计的,目前典型的产品有涡街流量计、旋进旋涡流量计。     

电导式相关流量测量传感器

在油水两相流条件下,水为连续相时,电导式传感器利用油相分布的离散性所造成的流体阻抗的随机变化检测流体流动噪声,通过对传感器中的上、下游传感器所检测出的流体流动噪声进行互相关运算,得到和流体流量相关的渡越时间,该传感器用于井下油水两相流量测量。文中给出了相关流量测量用电导式传感器检测流体流动噪声的原理、传感器中敏感器的结构及设计原则,同时给出了传感器激励源及信号处理电路的设计原则,文中最后给出了电导传感器在多相流模拟井上的流量测量实验及分析。     

高精度电容式压力传感器测量方法

提出了一种高精度、低成本的电容式压力传感器的测量方法。用RC振荡器将电容式传感元件的变化调制为时变频率信号,用SSP1492芯片测量该频率变化量,并送入C8051F021单片机,用高阶多项式完成频率变化到压力变化的解算,实现了高精度压力测量。实验结果显示:该方法用于电容式压力传感器的测量精度优于0.02%FS。     

一种新型硅电容式流速流向传感器的设计

设计了一种基于体微机械加工技术的新型硅电容式流速流向传感器.这种传感器由圆柱型阻流体和支撑梁构成,这种结构将流体的流速流向信息转化为阻流体的位移,通过四组正交电容来测量位移,从而得到流体的流速和流向.理论计算了传感器的结构尺寸并利用有限元分析方法计算了传感器的电容输出.     

微腔体内射流特性的研究

采用数值模拟的方法对微射流结构中的射流特性进行了分析研究,研究了射流管的长度、射流管截面形状、驱动振幅、驱动频率、气体介质及环境压强等对射流中心最大流速和流速轴向衰减指数的影响,为微射流结构的改进优化提供了依据.     

新型推力式流速传感器的测量原理与结构设计研究

提出了一种基于颗粒相特性进行流速检测的新型推力式流速传感器的实验装置结构.该流速传感器实验装置通过测量牵引线对置于流体中刚性浮球产生的拉力,再根据刚性浮球在流体中受力情况,计算得到流体对浮球的推力.最终利用推力和流体流速之间的经验公式得到流体流速.新型流速传感器结构简单,成本低,不仅可以测量一般河流、输水渠道、湖泊、海...     

High-Speed Flow Sensing as A Diagnostic Tool in the Development of Microfluidic Systems

Seyonic is developing a family of high-speed micro flow sensors with full-scale sensitivities between 0.25 and 10 microliter per second. The flow rate is determined by the measurement of a pressure difference across a fluidic restriction, using two integrated piezo-resistive pressure sensors. Main applications are in sub-microliter dispensing systems, where both sensor accuracy and speed provide real-time validation of the requested liquid volumes. The very fast response of the sensor, less than 2 ms, allows for measurement of liquid volumes down to the nL range. The sensor is able to measure not only the flow, but also the instantaneous pressure in the systems under evaluation. It is therefore possible to obtain valuable information on the system's operation for the characterization of fluidic components such as micromachined pumps, solenoid valves and jet dispensers     

A printed circuit board capacitive sensor for air bubble inside fluidic flow detection

This paper presents a three-electrode capacitive fluidic sensor for detecting an air bubble inside a fluidic channel such as blood vessels, oil or medical liquid channels. The capacitor is designed and fabricated based on a printed circuit board (PCB). The electrodes are fabricated by using copper via structure through top to bottom surface of the PCB. A plastic pipe is layout through the capacitive sensor and perpendicular to the PCB surface. Capacitance of sensor changes when an air bubble inside fluidic flow cross the sensor. The capacitance change can be monitored by using a differential capacitive amplifier, a lock-in amplifier, filter and an NI acquisition card. Signal is processed and calculated on a computer. Air bubble inside the liquid flow are detected by monitor the unbalance signal between the three electrode potential voltages. Output voltage depends on the volume of the air bubble due to dielectric change between capacitor’s electrodes. Output voltage is up to 53 mV when an 2.28 mm³ air bubble crosses the sensing channel. Air bubble velocity can be estimated based on the output pulse signal. This proposed fluidic sensor can be used for void fraction detection in medical devices and systems; fluidic characterization; and water–gas, oil–water and oil–water–gas multiphase flows in petroleum technology. That structure also can apply to the micro-size for detecting in microfluidic to monitor and control changes in microfluidic channels.     

插入式静电传感器空间滤波法流速测量

插入式静电传感器在测量煤粉流速和保证其安全输送有较好的应用。利用插入式静电传感器和空间滤波原理提出了一种新的测量固相颗粒传送速度方法。根据得到的插入式静电传感器的点电荷数学模型,推导得到了固相流速的空间滤波测量原理,同时,采用"3dB"原则获取信号的截止频率实现了固相流速在线测量。通过实验,验证了插入式静电传感器空间滤波原理的可行性,并在流速为2 m/s～7 m/s时,分别进行了实验验证。实测结果证实了插入式静电传感器空间滤波原理测量流体速度方法是一种有效的方法。     

Micro-molecular tagging velocimetry of internal gaseous flow

Dual-laser micro-molecular tagging velocimetry (μMTV) for internal gaseous flows on the microscale has been successfully demonstrated. MTV is a non-intrusive optical technique suitable for gaseous flow measurement by using molecules as tracers. In our dual-laser μMTV technique, seeded NO₂ molecules in a flow were tagged by photodissociation, producing NO molecules that can be distinguished from surrounding molecules. The tagged NO molecules were traced and visualized by laser-induced fluorescence. However, the fluorescence was in the deep ultraviolet region, and a reflective objective with a finite conjugate optical system was employed for imaging on the microscale. The seeded and tagged molecules of NO₂ and NO are stable in the gas phase at around room temperature and atmospheric pressure. Thus, this technique is free from condensation at the walls and is feasible for measurements of internal gaseous flow on the microscale. To demonstrate the validity of our dual-laser μMTV technique, the cross-sectional flow velocity profile in a rectangular microchannel and flow velocities in a micronozzle were measured and compared with numerical results.     

基于电容式传感器空间滤波效应测速原理分析

介绍了利用电容式传感器空间滤波效应测量固体速度的基本原理。推导出了极板对于介质脉冲信号的理论响应,并且求出电容式传感器的频率带度与固体与速度之间的关系。最后对此方法进行了讨论。     

形态滤波和空间滤波在两相流速度测量中的应用

为了快速、准确地对气固两相流速度进行测量,介绍一种利用形态滤波和空间滤波处理气固两相流信号的基本方法,首先研究电容传感器的空间滤波效应,并找出固体速度和电容传感器带宽之间的关系.然后通过对一维形态滤波算法理论进行分析,推导出可用于实时运算的形态滤波方法,此方法具有处理速度快,滤波效果好,适用性广的特点,可应用于多种信号的实时处理中.然后利用形态滤波确定传感器的带宽,进而求出固体速度.最后给出仿真实验结果,仿真实验结果表明:该方法可以满足气固两相流速度的测量要求.     

On combined use of pneumatic and hydraulic components in fluidics

The paper shows that in some cases the same fluidic device may usefully combine pneumatic and hydraulic components. This is illustrated by a number of examples. A jet-siphon liquid flow frequency transducer developed by the authors is considered where continuous flow is converted into discrete flow pulses by a siphon and the pulses are counted by a pneumatic device; a linear relationship between frequency of pulse alternation and flow is obtained in a liquid accumulator controlled by a pneumatic jet component. Other examples are given of the combined use of pneumatic and hydraulic components in automatic control devices in transducers, simulators, etc.     

暖通空调系统中新型传感器的应用

为优化暖通空调系统的运行效率,构建一种应用于暖通空调中新型超声波流量传感器,提出暖通空调系统中新型传感器的应用方法。首先根据传感器运行输入量和输出量两者之间的关系分析超声波流量传感器的静态特性和动态特性,并计算输入量及输出量的最大重复差。以此为依据分析传感器运行状态变化规律,并研究超声波流量传感器的传播速度和流速关系,将流速关系进行数字化处理,实现新型传感器的运行数值测定。通过实验与仿真进行传感器网络延时时长、声波传播速度、能耗对比测试与性能检测,结果表明,所提方法传感器网络生存期长、效率高、能耗低,具有一定的实用价值。