【作者】 卢丹；

【导师】 王福忠；

【作者基本信息】 河南理工大学 ， 控制理论与控制工程， 2009， 硕士

【摘要】 在固液两相流体流量的测量中,超声波多普勒流量计由于具有分辨率高,对流速变化响应快,对流体的压力、粘度和温度等因素不敏感的优点,从而得到了广泛应用。然而就当前测量水平来说,超声波多普勒流量计的性能还有待于进一步改进。本文首先针对固液两相流体的流速断面误差问题,提出了基于分区测速原理的流量测量方法。该方法把整个管流截面划分为若干个很小的信息窗区域,依据超声波多普勒测速原理,采用一个换能器发射信号,多个换能器接收信号的方式测量各信息窗区域内流体的流速值,然后利用“加权积分法”得到流体的流量。为了能有效地减小信息窗区域的尺寸,本文为发射换能器和接收换能器分别加装了平凹透镜和方向选择透镜,以此来提高各换能器对声波的指向性。其次,设计了一套完整的以TMS320LF2407A DSP为核心的超声波多普勒流量测量系统,从而满足了系统实时性的要求。硬件电路除了核心器件外,还辅以其它滤波及放大电路,其中采用GPRS无线通讯模块与上位机相连,实现了远程数据采集的功能;软件主要包括系统的主程序、监控程序、数据处理程序等。第三,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,主要处理技术是以快速傅里叶变换(FFT)为基础的周期图法和峰值逼近算法,再加适当的数字滤波技术,从而可以得到更加准确的多普勒频偏信号。最后,利用CCS2000和MATLAB软件以及THZK-1型测控技术综合试验平台,完成了系统的软硬件调试,并在自行搭建的试验管道上测得流量数据。试验结果证明,本课题的设计方案提高了超声波多普勒流量计的测量精度,达到了工业生产中对固液两相流体的测量要求。更多还原

【Abstract】 In the solid-liquid two-phase flow measurement, ultrasonic Doppler flowmeter is widely used because of its high resolving power, fast response with the variety of velocity, and insensitivity to the pressure and temperature of liquid. But now, technique in this field will be improved. Firstly, aiming at velocity profile error, this paper puts forward a measuring method for the flow of solid-fluid two-phase fluid based on zonal fluid velocity distribution measurement, by which the whole cross-section of fluid flow is divided into several information windows. According to the ultrasonic Doppler measuring principle, this method can measure the velocity value in each information window, using the manner of one transducer emits the wave ,which is received by multiple transducers. Then, to obtain the fluid flow by using weighted integral algorithm. In order to decrease the area of information windows and improve the directivity of each transducer, the emitter and the receiver are respectively installed with the plano concave lens and the choice direction lens. Secondly, in order to improve the real-time, designing of a complete measurement system based on TMS320LF2407A DSP. And in hardware design, low-pass filter, amplifier and other circuits are included. There using GPRS wireless communication module to connect with the host computer, can realize the function of remote data acquisition. The software included the main program, monitor program, data processing program and so on. Thirdly, digital signal processing is introduced to analyze Doppler signal, and the main processing technologies are periodogram method and approaching peak value algorithm, which are based on FFT. After this, digital filtering technique is in use. Thus more accurate Doppler frequency shift is obtained. Finally, debugging the software and hardware by CCS2000 and MATLAB, as well as the measure control technology synthesize experiment platform of THZK-1 type. Then measuring flow data from the test pipe. The test results prove that the whole desigen can improve the measuring accuracy of Ultrasonic Doppler flowmeter, which can reach the measuring requirement of solid-liquid two-phase fluid.更多还原