超声波流速测量的多普勒频移提取方法研究

为了提高超声波多普勒法测量复杂流体流量的精度,针对流体的超声回波频率的复杂性,本文研究多普勒流速测量中的频偏提取方法。以傅里叶分析为理论基础,设计了硬件电路并获得代表回波平均频率的信号,然后以该信号作为输入,以数字鉴频法获得回波多普勒频移。基于该方法设计了一种超声多普勒流量测量系统,实验结果显示:油水混合流体流量的测量误差在3%以内,从而证实了此频偏提取方法的有效性。

An extracting method of ultrasonic Doppler shift for multiphase fluid flow measurement

In order to improve the complex fluid flow measurement accuracy by ultrasonic Doppler method and to solve frequency complexity of the fluid ultrasound echoes, a mixed extraction algorithm for Doppler frequency difference value of echo is obtain to aim to the complex of ultrasonic echo for flow measurement. Based on the Fourier analysis theory, a hardware circuit is designed that is to obtain a signal representing the average frequency get an average frequency of the echo. And the significance of signal with this average is explained by Fourier transform algorithm. And then, the signal as an input to a digital frequency discriminator the Doppler frequency shift is to get. Basis of the design method above, an ultrasonic Doppler flow measurement system is designed. Experimental results show that the oil and water mixed fluid flow measurement error is less than 3%. Thus the validity of the frequency offset extraction method is confirmed.