【作者】 吴华玲；

【导师】 高松巍；

【作者基本信息】 沈阳工业大学 ， 测试计量技术及仪器， 2007， 硕士

【摘要】 超声波流量检测是根据超声波在流动的流体中传播的过程中会载有流体的流速信息这一原理，通过简便、可靠的信号处理方法，把这个流速信息转换成流量信息。超声波流量计与以往传统的流量计相比，具有费用低，安装简便，不会改变流体的流动状态，不产生附加阻力等优点，是一种非常理想的节能型流量计。然而，由于超声波流量计只是在近几十年才出现的一种新型仪表，还有很多地方不完善，没有得到普遍的应用，因而在科学技术迅速发展的今天，无论是对于自动化测量技术的提高还是对于环保事业来说，超声流量计的研究都将是一项极有意义的研究课题。本文详细介绍了超声波流量检测技术的基本原理和实现方法，在借鉴和吸收国内外先进的超声波流量检测技术的基础上，设计出了完整的系统硬件，并且给出了系统软件的设计思想。其中硬件系统以TI公司的DSP芯片TMS320LF2407A为核心，由于DSP芯片的信号处理速度快，就确保了本系统高的测量精度。硬件包括超声波信号的产生与功率放大、信号接收与放大，数据采集、存储、显示和DSP处理器系统；然后根据系统的硬件电路，引入先进的数字信号处理技术，在频域上对多普勒信号进行有效的处理；首先对多普勒频移信号进行采样，再进行FFT变换，进而得到该信号的功率谱，运用频谱细化分析方法对功率谱图进行分析，再加上适当的数字滤波技术，从而得到频移信号所对应的频率值，在此基础上，根据多普勒效应原理，求取管道中流体流速及其它数据量。系统能够完成对超声波信号的发射和采集，基本能达到设计要求，由于实验条件的限制，系统具体的精度指标还无法测出。最后文章给出了系统的改进意见。更多还原

【Abstract】 Both industrial production and scientific experimentation cannot go away with realization and control of flow. The ultrasonic flow measurement technology’s operating theory is that when ultrasonic pass the liquid, it carries out the signal reflecting the liquid’s flow velocity, and then, the signal will be used to compute the flow. Due to its advantage in accuracy, turndown ratio and no excess pressure drop, the current market for ultrasonic flow meter technology is growing rapidly in flow measurement. However, the ultrasonic flow meter develops just some ten years, and has not run in all fields it can be, so it provides many distinct and difficult challenges, and its significance not only to automatic measurement but to environment protection.The paper introduces basic principle and realizing method of the ultrasonic flow measurement technology. On basis of absorbing and referring to the domestic and foreign advanced ultrasonic flow measurement technology, the system hardware is designed and the idea of the system software is given. The core of the hardware is chip of TMS320LF2407A. High precision is guaranteed because of quick velocity of signal processing of DSP chip. Hardware includes generating and amplifying of ultrasonic, receiving and amplification of signal, data acquisition, Memory, display and DSP; on the base of hardware, Digital signal processing is introduced to analyze Doppler signal, for example, FFT is used to convert Doppler signal from time domain to frequency domain. After this, filter software is in use. Thus Doppler frequency shift is obtained. According to Doppler Effect, velocity and flux can be calculated.The system can transmits and receives the ultrasonic wave, the results of practical measurement and experiment show that the scheme has reached the requisition. Because of the restriction of experiment, the practice precision of the measure has not been measured.更多还原