超声波流量计通过超声波在流动的流体中传播载上流体流速信息，再通过简便、可靠的信号处理方法，就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，具有所要求的费用低，安装简便，不会改变流体的流动状态，不产生附加阻力，适合大管径大流量的测量等优点，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，非常值得去进行研究，这是本课题选题的一大因素。 本课题对超声波流量计的原理进行了阐述，设计并制作了超声波流量计。主要研究工作有：首先针对以往超声波流量计容易受温度影响而测量精度不高的问题，本文在一般声时差法的基础上，利用了声时差法的改进型算法，避免了温度变化对测量精度的影响；其次采用多声路方法进行流量测量，根据ORE 7500型流量计资料，推导出一种流量计算方法及各权重系数的取值法，减少了由于实际流体的流速分布不均匀而造成的测量误差，提高了测量的准确性与稳定性；接着，研究了超声波流量计工作环境以及安装中易出现的一些误差源，提出了种种改进办法，促进超声波流量计的可靠工作。然后，对流量计的上位机功能与算法进行了详细的设计，促使上位机软件的模块化编程，保证了使用者在Windows 2000系统下方便的对流量计进行操作；最后，设计并调试成功一台超声波流量计，该流量计的优点为：装置微机化，采用具有低功耗的微处理器进行控制、运算、数据处理，降低了整个系统的功耗，方便了与无电力保障的野外测量系统的配合； 通过大量的实验与运行结果表明，本课题中设计的超声波流量计的微机化设计、上位机软件设计等都达到了预期的效果，提高了超声波流量计的精度与稳定性。

Both industrial production and scientific experimentation cannot go away with realization and control of flow. The ultrasonic flow meter’s operating theory is that when ultrasonic pass the liquid, it carry out the signal reflecting the liquid’s flow velocity, and then, the signal would 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. That is one reason why this thesis chooses the topic. This thesis solves some measure problem in the traditional ultrasonic flow meter. First, an improved algorithm based on the common transit time method has been given to overcome the measure uncertain that temperature changing brings. Second, for one path ultrasonic flow meter always influenced by the flaw velocity profile, multi-path ultrasonic transducer arrangements method has been used to shorten the sensitive to installation effects. Third, some error source that would appear in ultrasonic flow meter working environment and in installation process have been discussed, and the way to overcome them also have been announced. Fourth, designs the software’s structure and algorithm, given the user facilities for controlling the flow meter. At last, use low power single chip doing measure, control, and calculation work, realizing the final design, an ultrasonic flow meter. A lot of experiment proves that the ultrasonic flow meter in this paper works well.