Blade Shape Optimization of Liquid Turbine Flow Sensor

Based on the characteristic curve analysis, the method using D(K^2) square difference of meter factor at different flow rates was developed to evaluate the performance of turbine flow sensor in this study. Then according to the distribution of entrance velocity, it was supposed that reducing the blade area near the tip could decrease the linearity error of a sensor. Therefore, the influence of different blade shape parameters on the performance of the sensor was investigated by combining computational fluid dynamics(CFD)simulation with experimental test. The experimental results showed that, for the liquid turbine flow sensor with a diameter of 10 mm, the linearity error was smallest, and the performance of sensor was optimal when blade shape parameter equaled 0.25.

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.

A 2-Dimensional Micro Flow Sensor with Wide Range Flow Sensing Properties

A new silicon micro flow sensor with multiple temperature sensing elements was proposed and numerically simulated in considering wide range flow measuring properties.The micro flow sensor has three pairs of temperature sensing elements with a central heater compared with typical sensor which has only a temperature sensing element on each side of a central heater.A numerical analysis of the micro flow sensor by Finite Difference Formulation for Heat Transfer Equation was performed.The nearest pair of temperature sensor showed very good linear sensitivity between 0 to 0.4m/s flow and saturated from 0.75m/s flow.However the furthest pair of temperature sensor showed some flow sensitivity even though the flow rate of 2.0m/s.Thus,this suggested new micro flow meter with multiple temperature sensing elements could be used as a thermal mass flow sensor which has accuracy sensitivity for very wide flow range.

The Flow Measurement of Multiphase Flow Based on the Conductance Sensor

Oil-gas-water three-phase flow in the pipe is commonly encountered in the petroleum and nature gas industry. Its flow patterns are complex and always changeable, so it’s difficult to be measured and is becoming one of the most important subjects. Moreover, most of the oil fields in China are in such a high water fraction period that measures must be taken to meet the needs of the actual production. A conductance sensor which is widely used in the measurements of oil-water two-phase flow is used to measure the flow rate of the three-phase flow based on the research of the characteristics and the correlation theory, and a new technical solution which is suitable for measuring the oil-gas-water three-phase flow is established. A series of tests demonstrate that it’s feasible to use the conductance sensor in the measurements of oil- gas-water three-phase flow.

A Combined Numerical-Experimental Study on the Noise Power Spectrum Produced by an Electromagnetic Sensor for Slurry Flow

The signals generated by electromagnetic flow sensors used for slurry fluids are often affected by noise interference produced by interaction with the slurry itself.In this study,the power spectrum characteristics of the signal are studied,and an attempt is made to determine the relationship between the characteristics of the related noise and the velocity and concentration of the slurry fluid.Dedicated experiments are conducted and the related power spectrum curve is obtained processing the signal measured by the sensor with Matlab.Numerical simulations are also carried out in the frame of an Eulerian approach in order get additional insights into the considered problem through comparison with the experimental results.The following conclusions are drawn:(1)The intensity of noise is directly proportional to the number of solid particles colliding with the electrode of the electromagnetic flow sensor per unit time,and to the square of the average velocity of the flow layer near the pipe wall.(2)With an increase in the slurry noise intensity,the power spectrum curve shifts upward in the logarithmic coordinate system(and vice versa).

Polymer-Based Micro Flow Sensor with Alternative Electronic Signal Interfaces for Low and High Flow Rates

The qualitative and quantitative assessment of gas flow has become increasingly relevant in the use of everyday systems. The micro flow sensor, developed by Innovative Sensor Technology AG （Switzerland）, is by principle a calorimetric flow sensor produced as a micro system on a glass substrate by means of photolithography and glass etching technology. These structures are arranged as a platinum micro heater and sensor in a Wheatstone bridge. The subsequent etching process produces an exposed area of polyimide membrane that is only a few microns thick and includes the resistive sensor structure as the active area. In addition, the RTD （resistance temperature detector） technology included on the sensor allows for the implementation of a variety of electronic biasing and signal processing modes. Since the sensor can be powered and the bridge can be measured in both CTA （constant temperature anemometer） and calorimetric mode, new possibilities are presented for both low and high flow rates with regard to temperature compensation, self-calibration and self-monitoring.

Simulation Method of Dynamic Characteristics of Turbine Flow Sensor

Computational Fluid Dynamics(CFD)simulation is one of the important methods to study the performance and influencing factors of turbine flow sensors.According to the working characteristics of the turbine flow sensor,the passive simulation method based on the six degrees of freedom(6-DOF)model and dynamic mesh is proposed in this paper.The reliability of the simulation method is verified by steady-state experiments 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,and the deviation between the simulation result and the experiment result is low with a maximum deviation of 2.88%.In the unsteady simulation study,the impeller speed changes with the inlet velocity of the turbine flow sensor,which has a good follow-up.The passive simulation method can be used to predict the dynamic performance of the turbine flow sensor.

Effects of water flow volume on the isolation of bacteria from motion sensor faucets

Water outlets for washing hands and medical equipment are essential for preventing hospital infection. The present study clarified the effects of water flow volume on the identification and quantitative evaluation of bacteria found around spouts in the 17 hand-washing stations. Pseu-domonas aeruginosa was detected from 4 sta-tions before adjustment and 2 after adjustment. Although no significant difference was identified in the detection rate of P. aeruginosa (p = 0.368), when combining P. aeruginosa and glucose non-fermentative Gram-negative bacilli (NFB), the number of stations with P. aeruginosa and/or NFB decreased significantly from 15 before adjustment to 9 after adjustment (p = 0.023). Before adjust-ment, quantity of bacteria was “2+” for 3 stations and “1+” for 7 stations, but was “1+” for 3 stations and “2+” for 0 stations after adjustment. These results show that quantity of bacteria could be reduced from spouts by adjusting flow volume. These results were also supported by experiments for cleanliness using Adenosine 5’-triphosphate bioluminescence me- thod.

Chemiluminescence flow Sensor for determination of the Ammonium ion

A novel chemiluminescence (CL) sensor for NH4+ combined with flow injection analysis is presented in this paper. It is based on the inhibition effect of NH4+ on the CL reaction between luminol, immobilized electrostatically on an anion-exchange column, and hypochlorous acid electrogenerated on-line. The sensor responds linearly to NH4+ concentration in 1.0x10(-6)-4.0x10(-9) g/ml range. A complete analysis could be performed in 1 min. The system is stable for 200 determination.

基于Inter-Flow网络编码的多Sink无线传感器网络Anycast路由

以最大化时间驱动型传感器网络的生命周期为目标,基于Inter-Flow网络编码,提出了多Sink环境下编码感知的交叉路径任播路由协议CodeMesh.首先分析多跳无线网络下单播流间编码条件,提出并证明了多Sink任播网络模型下的编码规则;进而提出多流编码簇的概念,以及确定编码簇个数和优化编码簇成员的方法;定义了统一量化编码和非编码路径代价,并综合链路质量、负载平衡和编码收益的路由度量;最后设计了兼具反应式源路由和主动式路由特点的任播编码路由协议.CodeMesh充分利用Sink节点丰富的计算和通信资源,将路由优化与重构、路由更新与维护与周期性数据收集过程相结合,大大降低了路由开销.部署于实验床平台的实验结果表明,CodeMesh能够有效寻找到具有最多编码机会的路径,从而减少数据传输次数,提高网络传输效率,同时平衡节点负载和能耗,延长整个网络的生存时间.

基于光电对射阵列下谷物收获流量控制系统的设计

在谷物收获过程中,由于谷物的性质不同及收获机械的工作状态不同,谷物的流量往往会出现波动或过大过小的情况,直接影响谷物的收获效率和质量,甚至会导致收获机械的故障。因此,对谷物的流量进行准确的控制和调节是非常重要的。为此,设计了一种基于光电对射阵列的谷物收获流量控制系统,可通过使用光电对射阵列检测收获机的运动状态和收获物料的流量,进而控制收获机的速度和工作状态,以实现谷物的准确收获和控制流量。试验验证表明:系统具有较高的准确性和稳定性,能够有效地控制谷物的流量,提高收获效率和质量,具有广泛的应用前景。

基于双螺旋式加热器的柔性MEMS流量传感器

针对传统流量传感器的量程限制,提出了一种基于双螺旋结构加热器的柔性基底微机电系统(MEMS)热式流量传感器。在基底上打出均匀通孔阵列以降低热传导损耗,两对测温电阻对称分布在加热器两侧,以获得较宽量程,在微小流量与大流量下均表现出较高灵敏度。采用基于惠斯通电桥的检测电路实现输出电压的测量,同时保持加热器与环境温度恒定温差200 K,对电阻自热进行补偿。传感器工作温度-100~400℃,量程为0~60 m/s;低流速下灵敏度约为12.75 V/(m·s^(-1)),分辨率可达0.001 mm/s,高流速下灵敏度约为1.4 mV/(m·s^(-1)),功耗低至1.3 mW。

The Measuring System for Estimation of Power of Wind Flow Generated by Train Movement and Its Experimental Testing

The measuring system for estimation of power of wind flow generated by the train movement has been created. The advantages of the proposed system are the cheapness and simple design. With its simplicity of design and easy build-up of channels, designed measuring system can be used for a wide range of technical problems. This paper describes the design process, validation and conducting the first field test of this measuring system.

基于SolidWorks Flow Simulation的矿用烟雾传感器气室结构流体仿真分析

针对矿用烟雾传感器气室结构容易进水且烟雾进出困难、影响烟雾传感元件响应时间的问题,为改善烟雾传感器气室结构对探测元件的影响并提高其防水性能,通过SolidWorks Flow Simulation对3种不同夹角投影的开孔气室结构进行流体仿真分析,研究了不同夹角开孔影响的气流、水流分布特征及变化规律。结果表明:气室结构设计为60°夹角投影的开孔防水、进烟雾程度对传感元件的影响最小,能极大地提高烟雾传感元件的检测灵敏性。

Experimental and Numerical Investigation of Swirling Flow on Triple Elbow Pipe Layout

The secondary flow downstream of a triple elbow layout was studied experimentally and numerically to visualize the flow behavior under swirling inlet flow conditions. The inlet swirling condition was generated by a swirl generator, consisting of a rotary pipe and honeycomb assembly. The experiments were carried out in turbulent water flow condition at Reynolds number Re = 1 × 104 and inlet swirl intensity S = 1. Ultrasonic measurements were taken at four locations downstream of the third elbow. The two-dimensional velocity field of the flow field was measured using the phased array ultrasonic velocity profiler technique to evaluate the flow field with separation. Furthermore, a numerical simulation was performed and its results were compared with the experimental data. The numerical result was obtained by solving three-dimensional, Reynolds-averaged Navier-Stokes equations with the renormalization group k-ε turbulence model. The experimental results confirmed that the swirling flow condition modified the size of the separation region downstream of the third elbow. A qualitative comparison between the experimental and CFD simulation results of the averaged velocity field downstream of the third elbow showed similar tendency on reverse flow.

Phase distribution in horizontal gas-liquid two-phase bubbly flow

An investigation on phase distribution in air-water two-phase flow in horizontal circular channel was conducted by using the double-sensor resistivity probe.The variations of phase distribution with variations of gas and liquid volumetric fluxes were analyzed and the present data were compared with some of other researcher’s data and existing models. It was found there exists more complicated phase distribution pattern in horizontal flow system than in vertical flow. The radial local void fraction profiles are similar at the same measurement angle with various gas and liquid flow rates. However, an asymmetric profile can be observed at a given slice of the pipe cross-section.

Comparative study of electrostatic sensors with circular and probe electrodes for velocity measurement of pulverised coal

This paper presents recent progress on the velocity measurement of pulverised coal in pneumatic pipelines using electrostatic sensors in combination with correlation signal processing techniques.A comparative study of electrostatic sensors with circular and probe electrodes was conducted on a 94 mm bore horizontal pipeline in a 4 MW furnace.The advantages and limitations of both sensors are discussed.Experimental results demonstrate that both sensors are capable of providing pulverised coal velocity measurement with excellent repeatability and dynamic response.

PB840呼吸机气路分析及故障维修

呼吸机是一种能替代患者自主通气的医疗仪器,广泛应用于呼吸衰竭患者、呼吸支持治疗以及急救复苏过程,是医院急诊、重症加强护理病房最重要的抢救仪器。本文介绍了2例PB840呼吸机故障,故障现象均为呼吸机报警、停止送气,报警代码相似。第1例故障经过呼吸机扩展自检(Extenden Self Test,EST)后分析自检数据,发现为呼出端流量传感器Q3故障,经过柠檬酸浸泡处理Q3后故障解除;第2例故障为氧气调零流量检测失败,具体原因为氧比例电磁阀故障,更换配件后故障解除。通过两例故障提示维修人员需熟悉仪器的气路图,熟练掌握呼吸机EST方法,提高维修准确度。

基于单片机开发板和3D打印的一种多参数呼吸训练装置的研究开发

目的通过野火骄阳32单片机开发板和3D建模及打印技术进行软硬件开发,实现一种多参数呼吸训练装置的专利样机转化。方法利用野火骄阳32单片机开发板开发应用程序,通过单片机开发板实现流量信号和压力信号的输入,舵机阀、涡轮风机、电磁阀的控制输出与上位机的数据通信等功能;样机非标零部件通过3D建模及打印技术完成制造,并将单片机开发板、标准零部件和非标零部件进行组合以完成样机开发。结果野火骄阳32单片机开发实现了传感器数据采集、运动部件的控制输出、上位机软件的数据上传和接收;3D建模及打印技术实现了非标零部件及机器外壳的制作,以低成本成功制作出样机;样机通过质控仪检测,流量值误差范围为±15%,气道压力值误差范围为±[2%FS(满量程)+4%×实际读数],样机参数精度满足JJF1234-2018《呼吸机校准规范》要求。结论野火骄阳32单片机开发板和3D建模及打印技术的应用,以低成本实现了样机制作,能够为专利的商业转化提供重要参考,为医工专利转化提供了一种新的思路。

改进流向算法的无线传感器网络覆盖优化

针对标准流向算法易陷入局部最优和收敛精度低等问题,提出一种融合莱维(Levy)飞行和入侵杂草策略的改进流向算法.首先,该算法在选择水流流向时引入Levy飞行机制,使水流沿最优水流位置方向做Levy飞行运动,避免陷入局部最优;其次,利用入侵杂草策略,对每一代水流进行繁殖、空间扩散和竞争操作,增加水流的多样性,扩大搜索范围,提高全局寻优能力.最后,将改进流向算法应用于无线传感器网络覆盖优化中,并与标准流向算法及其他改进算法进行实验对比.仿真结果表明,相比标准流向算法及其他改进算法,所提改进流向算法的覆盖性能有大幅提升,覆盖率可达98.52%,可实现更均匀的节点分布和更低的部署成本.