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1.
《机械》2017,(3)
根据管道低温流体多相流输运过程控制技术特点,设计了中流式低温过程控制减压节流阀,用于解决变压、变温、变流量的管道制冷过程中的低温流体输运带来的技术难题,减少低温流体输运过程中的动能损失及动密封泄漏问题,提高管道内低温流体过程控制及相变制冷效率,实现低温流体管道内减压与节流制冷过程的相对稳定。  相似文献   

2.
丁海平 《阀门》2002,(3):1-3,9
止回阀一般安装在流体输送机泵出口管道及防止流体逆流的管道上,通过对管道系统中的止回阀在下游阀门短时间内关闭时的水击模拟分析,提出在止回阀设计中应考虑水击压力对阀门过载和疲劳破坏的影响以及止回阀结构对管道系统产生水击的作用。  相似文献   

3.
工业生产中常采用设置缓冲器来消减压缩机管道系统内的气流脉动和减小管道振动。但是工厂投入使用的缓冲器,缓冲容积普遍偏小,或者安装位置离压缩机气缸进出口太远,导致缓冲效果不理想。针对上述问题,利用流体仿真软件FLUENT建立了管道内气体的三维非稳定流动模型,计算了缓冲器和孔板对管道内气体压力脉动的影响;并在大量仿真实验的基础上,利用MATLAB软件拟合出缓冲器进出口压力变化和体积的关系曲线,从而实现对缓冲器体积的优化设计。  相似文献   

4.
超声波流量计通常由超声波换能器、电子线路和显示系统三部分组成,由于超声波换能器的安装结构限制,超声波流量计很难用于测量高温管道中的高温流体。本文将通过对超声波换能器安装结构进行设计,使超声波流量计能适用于测量高温流体,并通过有限元仿真计算分析,验证这种结构的可行性。  相似文献   

5.
对管道气体流场模型进行了说明.空气质量传感器安装在滤清器出口的进气管道中,用Fluent仿真软件对模型做流场分析,改变传感器水平方向和垂直方向的安装位置,得出多组速度数据进行比较分析,确定其最优安装位置.仿真结果表明,随着传感器的垂直方向安装位置从管道底部向管道顶部的上移,且水平方向安装位置从滤清器出口向外移,其热电阻表面流场的同一水平方向的速度一致性变好,但垂直方向速度梯度变大,兼顾速度一致性和速度梯度,得到传感器的热电阻处于管道中心垂直往上h,且距离滤清器出口1.3H的优化位置.  相似文献   

6.
气力输送中变径管道系统设计的研究   总被引:3,自引:2,他引:1  
介绍了气力输送中变径管道的设计方法和主要参数(临界速度、管径、压降、气体流速、变径位置、变杆角)的确定。通过分析实验数据,说明采用逐渐增大管径的变径管道可以有效地降低输送管道中的气速、压损和能耗。  相似文献   

7.
过程控制实验平台的设计与实现   总被引:1,自引:0,他引:1  
于亚利  武丽 《机电工程》2010,27(8):36-38
针对我校过程控制实验场地、实验设备有限等问题,首先设计开发了一套过程控制实验平台。该实验平台下位机采用S7-300PLC控制器,对实验对象直接进行控制;上位机选择的是WinCC组态软件,通过与下位机通信,从而实现了对实验对象的控制、报警显示以及实时数据的显示和记录等功能。该实验平台的实验对象主要包括高位溢流水箱和夹套锅炉,能够实现液位、流量、温度和压力等参数的单回路、串级和反馈-前馈等控制。然后通过实验平台对锅炉液位进行控制,给出了相应的控制结果。研究结果表明,该实验平台为过程系统的网络化控制奠定了基础。  相似文献   

8.
流体传输中流体阻力和水头损失的计算   总被引:1,自引:0,他引:1  
分析了流体在传输过程中流体阻力的种类,介绍了流体在管道中处于层流或者紊流状态时流体流速的表达式和水头损失的计算公式,给出了传输管件、附件等局部阻力系数及水头损失计算的方法。通过研究流体阻力,可以正确计算传输系统中的阻力;找出减少流动阻力的途径;利用阻力所形成的压差Δp来控制某些元件的动作。最后,提出了减小水头损失的途径。  相似文献   

9.
实际工程中,大多数的石油运输管道只允许安装压力传感器检测泄漏情况,流量计仅安装在收费口处,而且对于不可压缩流体无法通过临界压力条件计算泄漏量。基于应力应变公式,通过研究管道的微元体受压时管壁的径向位移与管内压强的关系,得出管道体积随管道压力的应变响应。以管道容积膨胀的改变量表征管道中不可压缩流体的泄漏量,得到不可压缩流体的泄漏量计算模型。建立管道受压膨胀的COMSOL模型进行仿真验证,仿真结果和推导公式均表明管道的体积应变与管道压力呈二次抛物线关系,但当管道内压力变化不大时,二者之间可近似为线性关系。此外,建立实验平台得到了压力为0 MPa~0.8 MPa时的泄漏量,验证了不可压缩流体与压力变化之间的线性关系。理论和实验结果为管道内不可压缩流体泄漏量的计算提供了理论依据。  相似文献   

10.
实际工程中,大多数的石油运输管道只允许安装压力传感器检测泄漏情况,流量计仅安装在收费口处,而且对于不可压缩流体无法通过临界压力条件计算泄漏量。基于应力应变公式,通过研究管道的微元体受压时管壁的径向位移与管内压强的关系,得出管道体积随管道压力的应变响应。以管道容积膨胀的改变量表征管道中不可压缩流体的泄漏量,得到不可压缩流体的泄漏量计算模型。建立管道受压膨胀的COMSOL模型进行仿真验证,仿真结果和推导公式均表明:管道的体积应变与管道压力呈二次抛物线关系,但当管道内压力变化不大时,二者之间可近似为线性关系。此外,建立实验平台得到了压力为0 MPa~0.8 MPa时的泄漏量,验证了不可压缩流体与压力变化之间的线性关系。理论和实验结果为管道内不可压缩流体泄漏量的计算提供了理论依据。  相似文献   

11.
一个用于化学热泵的分布式测控系统   总被引:1,自引:0,他引:1  
基于RS-485总线,对一化学热泵装置设计相应的分布式测控系统,实现了在线自动测量和控制,获得完整的实验数据,为热系统的优化控制奠定了基础。  相似文献   

12.
针对工业现场超声波流量计要求较高精度,简化现场布线,对安装现场进行监控预警又要远距离传输数据的需求,设计了一种基于物联网MQTT协议和ESP8266芯片的高精度超声波气体监控系统。使用DHT22测量温湿度、MQ-4测量甲烷浓度。为提高超声波流量计的精度,使用Z式探头安装法与MAX35104高精度气体测量芯片。采用STM32F103ZET6作为主控MCU,实现对外围电路的控制及数据处理。为实现远程控制与无线传输数据,采用ESP8266芯片通过网络传输数据。实验证明,该系统实现了测量现场的布线简化、危险环境监控和远程数据传输,可以进行气体流量测量,成本较低,可靠性高。  相似文献   

13.
In this paper, an unsteady flow measurement standard device is studied and designed. The device can be used to measure the flow rate of any liquid medium. First, through comparative analysis of the design scheme of the unsteady flow measurement standard device, the structure of the active piston type is determined, and the schematic diagram is designed. According to the schematic diagram, the mathematical model of the device based on the active piston is established, and the uncertainty of the device is evaluated. Second, the hardware control system is designed and built according to the uncertainty evaluation results. Then, the upper computer operating system of the device is constructed, and a highly integrated human-computer interaction data acquisition and control system is established. Finally, the measurement performance of the device is verified by comparing the set value with the measured value of flow rate, and the uncertainty of the device is analyzed. The combined standard uncertainty can meet the expected value of 0.5%.  相似文献   

14.
This study was designed to identify the suppression characteristics and mechanisms of flow-induced vibration occurring in a test cylinder installed on an elastic support by placing a control cylinder with a smaller diameter behind the test cylinder. To identify the effects of this installation, the diameter and location of the control cylinder were varied systematically to examine the characteristics of flowinduced vibration occurring in the test cylinder. Furthermore, the fluctuating streamwise velocity of the wake flow of the test cylinder was examined as it varied with the installation of the control cylinder. Subsequently, the peripheral flow of the test cylinder installed in front of the control cylinder was examined via a flow visualization test that used a water channel. Results obtained from the experiments are summarized as follows. i) Flow-induced vibrations in the test cylinder, which occur and are varied by the installation of the control cylinder behind the test cylinder, have four types that change according to the different diameters and locations of the control cylinder. ii) The domain of the positions of the control cylinder, which can suppress flow-induced vibration in the test cylinder, increases in proportion with the diameter of the control cylinder. iii) Flow-induced vibration that will be generated in the test cylinder is predicted by examining the distribution of the flow velocity of the wake flow and the intensity of the fluctuating streamwise velocity at the lower flow velocity level before it reaches a flow velocity that can create flow-induced vibration in the test cylinder.  相似文献   

15.
王学军  袁健康 《仪器仪表学报》1999,20(4):356-359,363
本文提出了采用光电技术非接触曲面自动测量三维曲面的一种方法,介绍了光电三维曲面测量仪的系统设置。光学角测量原理,光电系统参数的优化设计,计算机模拟测量,计算机自动测量过程与控制和测量数据采集与处理方法。通过对位移和轿车模型曲面的实测和分析,在一定的测量范围内具有较高的精度。  相似文献   

16.
土壤源热泵系统埋地换热器换热性能研究   总被引:2,自引:0,他引:2  
对土壤源热泵系统埋地换热器的影响因素进行研究,分析三种获得土壤热物性参数的方法,得到利用现场测试法较精确.搭建实验台对埋地换热器传热量进行测试,发现室内负荷和埋管循环水流量对埋地管与土壤的换热量影响较大,利用圆柱源传热模型进行模拟验证,模拟结果与实验结果吻合较好.  相似文献   

17.
A novel system [field and laboratory emission cell (FLEC) automation and control system] has been developed to deliver ozone to a surface utilizing the FLEC to simulate indoor surface chemistry. Ozone, humidity, and air flow rate to the surface were continuously monitored using an ultraviolet ozone monitor, humidity, and flow sensors. Data from these sensors were used as feedback for system control to maintain predetermined experimental parameters. The system was used to investigate the chemistry of ozone with alpha-terpineol on a vinyl surface over 72 h. Keeping all other experimental parameters the same, volatile organic compound emissions from the vinyl tile with alpha-terpineol were collected from both zero and 100 ppb (parts per 10(9)) ozone exposures. System stability profiles collected from sensor data indicated experimental parameters were maintained to within a few percent of initial settings. Ozone data from eight experiments at 100 ppb (over 339 h) provided a pooled standard deviation of 1.65 ppb and a 95% tolerance of 3.3 ppb. Humidity data from 17 experiments at 50% relative humidity (over 664 h) provided a pooled standard deviation of 1.38% and a 95% tolerance of 2.77%. Data of the flow rate of air flowing through the FLEC from 14 experiments at 300 ml/min (over 548 h) provided a pooled standard deviation of 3.02 ml/min and a 95% tolerance range of 6.03 ml/min. Initial experimental results yielded long term emissions of ozone/alpha-terpineol reaction products, suggesting that surface chemistry could play an important role in indoor environments.  相似文献   

18.
针对国家环保总局提出的有效监测和控制烟尘排放的要求,设计以光后向散射法为原理的烟尘检测仪.介绍系统的原理和构成,及其安装与校准.系统不仅可以实时、在线和连续测量,而且现场安装简便.经过现场测试研究证明:系统的灵敏度高,精确度高,可靠性好,其线性回归方程的相关系数达到0.99,为该领城的研究人员提供了实践依据.  相似文献   

19.
超声波气体流量计的管道模型仿真和误差分析   总被引:9,自引:5,他引:4  
为满足不断发展的超声波气体流量计测量精度的需要,改进传感器的设计精度和有效降低安装测试及样机调试成本,针对制约超声波气体流量计测量精度主要误差源之一的管道流场分析问题,结合计算机建模数值仿真技术及实验技术对其流场设计参数以及弯管安装条件等对超声波测量误差产生原因进行定量分析.理论研究和仿真实验结果表明,可以量化分析气体超声波流量计流场误差产生的原因、范围,并通过限定流场修止系数更有效地降低其测量误差,这项研究对该超声波气体流量计的优化设计和工程应用具有一定的指导意义.  相似文献   

20.
Subways are a major mode of public transportation in metropolitan cities. A proper ventilation system is required to maintain indoor air quality in subway tunnels. Platform screen doors improve the platform environment but degrade air quality in subway tunnels. Trains transport fine particles from the tunnel into the platform. An air curtain installation in the subway tunnel permits traffic and reduces the transfer of bacteria and fine particles. The existing tunnel of Seoul subway was investigated by using computational fluid dynamics and design of experiment method for optimum air curtain installations. The flow field of the subway tunnel was computed by using ANSYS CFX software. Minitab software was used to generate the design process and to analyze the computational results. The computational domain of the existing tunnel included two natural ventilation shafts, one mechanical shaft, and the twin tracks. The height, width, and length of each track were 6, 4, and 400 m, respectively. The air curtain installation area was located between the natural and the mechanical ventilation shafts of Rrack 1. The design variables for the optimization study were the width, velocity, and installation location of the air curtain. The object function for optimization was mass flow rate at the natural ventilation shaft. The length of the air curtain was fixed at 4 m. The predicted mass flow rates were analyzed with the design variables by using the response surface method (RSM). The optimum values of the design variables, i.e., velocity, width, and installation location were 25 m/s, 0.2 m, and 5.8195 m, respectively. The maximum mass flow rate with the optimum design values was 114.4447 kg/s. The optimum values of the design variables were validated by computing the tunnel with the optimum values from RSM. The mass flow rate in the natural ventilation shaft 1 was 114.2 kg/s, as predicted. The optimization study can be helpful to set the optimum design conditions for the subway ventilation system.  相似文献   

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