气动元件流量特性分析及实验研究
Study on Flow-Rate Characteristics and Test Methods of Pneumatic Components

针对气动元件流量特性曲线的形状、形成机理以及ISO6358标准中测试方法存在的问题,运用理论与实验相结合的方法,研究了临界压力比两种取值方法间的关系,发现了特性曲线中流量不变段与下降段的分界点并不是元件内声速流与亚声速流的转折点,提出在气动元件流量特性的测试中,须对被测元件的上、下游压强进行补偿。实验结果表明:特性曲线中的下降段部分近似为椭圆曲线,临界压力比两种取值结果间的差值约为0.15,特性曲线中的下降段并不只代表亚声速流态,还包含了由超声速变化到声速的过程,忽视压强补偿导致测试结果的误差达15％以上。
A theoretical？？experimental method is used to study the shape, forming mechanism of flow？？rate characteristic curves and some existing problems of test methods specified in ISO6358. It is found out that the cut？？off point of the flow？？rate in characteristic curve is obviously different from the transitional point of airflow velocity in pneumatic components by studying the relationship between two different methods to calculate critical back？？pressure ratios. Moreover, it is proposed that it is necessary to compensate the measured upstream and downstream pressures of components under test. The experimental results show that the difference between critical back？？pressure ratios obtained from the two methods is about 0.15, and the fallen section of the flow？？rate characteristic curve includes not only the state of subsonic but also a change process from supersonic to sonic. Furthermore, the subsonic index m≈0.5, that is, the fallen section of the curve is an approximate elliptic curve. It is also found out that a 15% error appears when the influence of pressure compensation is ignored