管道液体流速在线测量系统设计大学学位论文.doc

管道液体流速在线测量系统设计 摘 要 在科技飞速发展的当今社会，流速测量广泛应用于工农业和医学，管道液体流速的测量是液体流速测量的一个方面的应用。管道流速测量主要利用超声波多普勒效应测量，入射波和反射波的频差来进行流速的测定，当超声波声源和反射界面或者散射体之间存在相对运动时，被反射或被散射的超声波信号的频率将发生变化，该频率与声源超声波频率之间的差值与相对运动的速度成正比，这一现象称之为多普勒效应。接收信号的频率与声源的频率之差称为多普勒频移；相应的频差信号称为多普勒信号。当流体存在着可反射或散射超声波的跟随粒子时，便可以利用多普勒信号确定流体的速度。具有空间频率高，能进行非接触的测量，不需要校正、响应特性好，应用范围宽等特点。 【关键词】 管道液体流速，超声波多普勒，多普勒信号 Abstract In the rapid development of technology in todays society, the flow rate measurement is widely used in industry, agriculture and medicine, pipe liquid flow rate is measured liquid flow rate measuring one aspect of the application. Pipe flow measurement using ultrasound Doppler effect mainly measured incident and reflected waves of the frequency difference between the flow rate measurement for, when the ultrasonic sound source and the reflector or the relative motion between the scattering when the ultrasonic wave is reflected or scattered will change the frequency of the signal, the frequency of the sound source and the difference between the ultrasonic frequency proportional to the speed of relative motion, this phenomenon is called the Doppler effect. Frequency of the received signal of the difference between the sound source frequency is called the Doppler frequency shift; corresponding difference signal is called the Doppler frequency signal. When the fluid there may be an ultrasonic wave is reflected or scattered particles to follow, can take advantage of the Doppler signal to determine the fluid velocity. Having a high spatial frequency can perform non-contact measurement, no correction, the response characteristics of a good, wide range of applications and so on.[Keywords] pipeline fluid velocity, Doppler ultrasound, Doppler signal  目 录 绪论 4 1.1流速的概述 4 1.2液体流速测量的概况 4 1.3 管道液体流速测量的研究意义及发展 5 超声波多普勒测管道流速原理 6 2.1超声波传感器的基本原理 6 2.2多普勒效应测流速原理 6 超声波多普勒测管道流速设计 8 3.1超声波发射模块设计 8 3.2超声波接收模块设计 8 3.2.1选频放大电路 8 3.2.2解调电路 8 3.2.3低通滤波器的设计 9 3.2.4放大电路的设计 9 超声波多普勒测管道流速设计思想 10 5总结 11 致谢 11 参考文献 11 绪论 1.1流速的概述 流速是指气体或液体流质点在单