平衡型节流器件中液氮流动实验研究

Experimental study for liquid nitrogen flow in balanced orifice plate

以平衡型节流器件为主要部件的多孔节流流量计在低温液体流量测量上具有显著优点。本文搭建了真空可视化实验平台,采用高速相机对以液氮为工质的水平管内流动形态进行了观察,并分析了液氮在平衡型节流器件中的流动特性,结果表明:液氮进入常温管道后,依次出现了单相气氮流动(分为常温单相气氮和低温单相气氮流动)、气液分层流、波状流、弹状流、单相液氮流动等流型;实验标定的节流器件流出系数在流量测量范围内保持稳定;液氮流经平衡型节流器件后的永久压力损失随着速度增大而增加,并呈良好的抛物线形关系。

he balanced orifice plate,the main part of multi-orifice throttle meter,has significant advantages in the cryo⁃genic liquid flow measurement.This article built a vacuum visualization experimental platform,the flow pattern inside a horizon⁃tal tube was observed by a high-speed camera using liquid nitrogen as the working fluid,and the flow characteristics were ana⁃lyzed in the balanced orificeplate.The results indicate that after liquid nitrogen flow into the normal temperature pipe,the flow pattern presents single nitrogen flow(include at normal temperature and at cryogenic temperature),gas-liquid stratified flow,wavy flow,slug flow and single liquid nitrogen flow.The discharge coefficient of the balanced orifice plate was obtained by liquid nitrogen flow,and maintains stability within the flow measurement range.The permanent pressure drop produced by liquid nitro⁃gen flow through the balanced orifice plate increases as the velocity increases,and it presents a good parabolic relationship.