| 什么是孔板流量计的节流装置，如何定义 |
| 信息来源： 液位变送器 | 2019-04-17 点击量： 4786 |
什么是孔板流量计的节流装置，我们应该去如何定义？西安华恒仪表制造有限公司介绍：
What is the throttling device of orifice flowmeter and how should we define it?Xi'an Huaheng Instrument Manufacturing Co.,Ltd.
孔板流量计是将标准孔板与多参数差压变送器(或差压变送器、温度变送器及压力变送器)配套组成的高量程比差压流量装置，可测量气体、蒸汽、液体及引的流量，广泛应用于石油、化工、冶金、电力、供热、供水等领域的过程控制和测量
Orifice plate flowmeter is a high range ratio differential pressure flowmeter which is composed of standard orifice plate and multi-parameter differential pressure transmitter(or differential pressure transmitter,temperature transmitter and pressure transmitter).It can measure the flow of gas,steam,liquid and drainage.It is widely used in process control and measurement in petroleum,chemical industry,metallurgy,electric power,heating,water supply and other fields.
管道的前后压差较大时，往往采用增加节流孔板的方式，其原理是:流体在管道中流动时，由于孔板的局部阻力，使得流体的压力降低，能量损耗，该现象在热力学上称为节流现象。该方式比采用调节阀要简单，但必须选择得当，否则，液体容易产生汽蚀现象，影响管道的安全运行。
When the pressure difference between the front and back of the pipeline is large,the throttle orifice plate is often added.The principle is that when the fluid flows in the pipeline,the local resistance of the orifice plate reduces the pressure and energy loss of the fluid.This phenomenon is called throttle phenomenon in thermodynamics.This method is simpler than using control valve,but it must be selected properly.Otherwise,the liquid is prone to cavitation,which affects the safe operation of the pipeline.
节流孔板的作用，就是在管道的适当地方将孔径变小，当液体经过缩口，流束会变细或收缩。流束的最小横断面出现在实际缩口的下游，称为缩流断面。在缩流断面处，流速是最大的，流速的增加伴随着缩流断面处压力的大大降低。
The function of throttle orifice plate is to reduce the diameter of the orifice in the proper place of the pipeline.When the liquid passes through the shrinkage orifice,the flow beam will become smaller or shrink.The minimum cross-section of the beam appears downstream of the actual contraction,which is called the contraction cross-section.At the condensation section,the velocity is the largest,and the pressure at the condensation section decreases greatly with the increase of the velocity.
当流束扩展进入更大的区域，速度下降，压力增加，但下游压力不会完全恢复到上游的压力，这是由于较大内部紊流和能量消耗的结果。
When the beam expands into a larger region,the velocity decreases and the pressure increases,but the downstream pressure will not completely restore to the upstream pressure,which is due to larger internal turbulence and energy consumption.
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