层流流量计的研究与应用

对脉动气流所作的理论分析说明，可以直接用于脉动气流测量的流量计必须具备两个条件：流速与所测参数之间应有线性关系，以及二次仪表应能反映出所测参数对时间的平均值。层流流量计就是靠由许多小流道构成的层流元件和在测压接头内装有阻尼元件来到这两条件的。文中讨论了层流元件的选型、流量计的设计方法以及层流元件加工等问题。雷诺数R e、R e与当量直径d d与元件长度l的比值的乘积R e·l/d d保持流速与测量段压差为线性关系的两个最重要的条件。文中并从理论上说明了获得层流量计的标准特性以及正确使用时的换算公式（30）和（31）式。所研制的D-100层流流量计，曾在195、295和395柴油机试验台上进行试验，在不用稳压箱的情况下，误差小于1～2%，从而证实了层流流量计直接用于测定脉动气流平均流量是简便而有效的。

The Research and Application of Laminar Flowmeter

From the analysis of pulsating flow, it is shown that the direct application of flowmeter to the pulsating fluid flow measurements must has two conditions, namely the relocity is proportional to the measured parameter and the reading of the measured parameter is the mean valule of time. To attaining these two conditions, laminar fi_owmeter depends on the laminar element consisting of a number of narrow passages, and the measuring pressure tube with damping element. The choosing of structure tupes of laminar elements, the design method of laminar flowmeter and the process of the laminar elements and disussed in details. The upper limited valules of Reynolds number Re and Re R e·l/d d equivalent diameter, the length of element) are very important paraments for holding the linear relation between the velocity and pressure drop in the measuring range. For establishing the standard characteristic and using the laminar flowmeter more accurately, the formulue (30) and. (31) are necessary.The D-100 laminar flowmeter designed by authors was experimented on the 195, 295 and 395 Diesel engine test beds. The reading errors of this laminar flowmeter applied directly to measuring the pulsating air mean flow are less than 1-2% comparing with the readings of using plenum camber (damping pressure pulsaitng box). Therefore laminar flowmeter is simple and effctive for pulsating mean flow measurements.