【摘要】 针对传统流量计在测量流体流速时存在安装繁琐、运输复杂等问题,设计了新型的基于多普勒法的超声波流量计。该系统以STM32为开发平台,主要设计了超声波发射电路、超声波接收电路、功率放大电路、回波信号处理及滤波电路、STM32最小系统及其外围电路等。为方便频移信号处理,提出了把回波信号解调到中频带20 k Hz上,这样提高了系统在低流速测量的精确度。采用FFT算法对系统采集的频移信号进行频谱分析,最终根据计算的频移值来确定流体的流速。实际结果表明,该系统尤其适用于大管径流量测量且测量精确度较高,误差在5%之内,具有安装、运输便捷等一系列优点。更多还原

【Abstract】 A new type of ultrasonic flowmeter based on Doppler method was designed for the traditional flowmeter had the problem of complicated installation and transportation in the measurement of fluid flow velocity. The system used STM32 as the development platform,mainly designed ultrasonic transducer transmitting circuits receiving circuits,power amplifier circuit,echo signal processing and filter circuit,STM32 minimum system and its peripheral circuit. In the frequency-shifted signal processing,it was proposed to demodulate the echo signal to the middle band 20 k Hz,which improved the system in the low flow rate measurement accuracy. The FFT algorithm was used to analyze the frequency shift signal collected by the system. Finally,the velocity of the fluid was determined according to the calculated frequency shift value. The actual results show that the system is especially suitable for large diameter flow measurement and measurement accuracy is high,the error is within 5%,with installation,transportation and a series of advantages.更多还原