【作者】 何群；

【导师】 赵春晖；

【作者基本信息】 哈尔滨工程大学 ， 通信与信息系统， 2004， 硕士

【摘要】 超声波流量计以其非接触、易于安装维护的优点在工业测量领域获得了广泛的应用。然而超声波流量计本身也存在许多不足之处，因此有必要对其加以改进和提高，以使其工作性能更加稳定，可靠。本论文就是以此为出发点，以时差式超声波流量测量系统为研究对象，对能提高整个系统性能的几项关键技术进行了深入的理论研究，并给出了具体电路实现方法。主要工作如下： 1．研究了时差式超声波流量计的测量原理，对理论公式进行了推导并给出了时差法超声波流量的测量原理图。然后根据流体力学的有关知识，对管道流体流速分布规律特别是流速分布修正系数进行了讨论。最后从理论上对超声波在流体中的传播特性进行分析，为具体的电路实现打下了坚实的理论基础。 2．讨论整个系统硬件电路的几个关键技术及其实现方法，包括换能器的结构和参数选择、应用范围门检测理论的信号检测电路以及采用复杂可编程逻辑器件(CPLD)完成对发射驱动电路的改进和传播时间的精确测量。 3．本文针对工业仪表要求键盘操作方便、简捷这一特点，结合软件工程学中先进的结构化分析方法与结构化设计技术，超脱具体检测／控制对象，从一般意义上对通用键盘的软件设计方法进行了研究。 4．对影响流体流量测量的各种因素进行了仔细的分析、研究，采用突出主要误差的分配原则，对各种可能误差进行了误差合成。最终给出了实验结果。更多还原

【Abstract】 Ultrasonic flowmeter is applied widely in industrial measurement field for the two advantages, non-contact and installation and maintenance with ease. However, it also has some disadvantages, thus it is necessary to make modification and advance in order that it can work more stable and tried. This is the intention of this article, whose study object is time-difference-type ultrasonic flow measurement system. The article makes deeply theoretical research on several vital techniques to advance the capability of the whole system. In addition, it supplies methods of concrete cicuits’ realizing. Generally, there are four parts as the following:1. Research the measurement theory of time-difference-type ultrasonic flowmeter, derivate the theory formula and show the measurement theory figure of time-difference-type ultrasonic flowmeter. Then discuss the distribution regularity of flow velcocity of piping fluid, especially revision coefficient of flow velcocity distribution according to correlative knowledge in hydromechanics. Eventually propagation character of ultrasonic in fluid is analyzed theoretically, which lays a solid foundation in theory for concrete circuit’s realization.2. Discuss some vital techniques and their realization methods of hardwares in the whole system, including transducer’s structure and parameter choice, signal examination circuit that is applied range examination theory and with CPLD improvement on launching driver circuit and precise measurement on propagating time.3. To counter that industrial meter require easy and simple operation of fingerboard, the article has a research on the software design method of common fingerboard, while combining advanced structure analysis method and structure design technique in software engineering, detaching concrete examination/controlled object.4. Analyze and study various factors which influence flow measurement. According to the distribution principle which is to stress main errors, compose all possible errors. In the end, the experience result is achieved.更多还原