Study On Doppler Ultrasound Measurement Technology For Certain Fluid Flow

Doppler ultrasonic flowmeter is a novel type flow meter. Measuring the fluid flow rate suitable liquid contained solid particles and air bubbles. However, due to the Doppler shift is difficult to capture, so the measurement accuracy of the Doppler method is lower than the transit-time method. Therefore, studies on the ultrasonic Doppler flowmeter, especially for denoising, extraction and processing calculations of the Doppler shift signal are necessary. This paper studies an ultrasonic liquid flow precise data processing method. This paper studies a data processing method for ultrasonic liquid flow. The new method includes the frequency conversion design by hardware and the average frequency-shift calculation by software. The shortages of Doppler flow measurement, such as low accuracy and error are solved. The main works are as follows:1. It is introduced for the measuring principle and characteristics of ultrasonic flowmeter, and proposes methods of an ultrasonic liquid flow precise data processing.2. Extract the signal of ultrasonic Doppler shift. Selection 2MHz ultrasound can identify particles which size is dmm(decimillimetre). The using the flow rate information from the smaller particles-feedback, so that decreases error of flow rate. Used of a combinational circuit which include mixer based on analog multiplier and low pass filter. Achieved Doppler shift signal extracted in the echo signal. This avoids the computationally intensive and long operation time of the shortcomings because of high sampling frequency. Thereby, this work will be increasing the real-time of flow rate information and accuracy of instantaneous flow measurement.3. Process the signal of ultrasonic Doppler shift. Doppler shift is processed by the ADC and digital filtering. Especially digital filter is designed based on ABC algorithm. It can reduce the noise signal effectively. Used FFT algorithm can be obtained the Doppler shift of the power spectrum. The average frequency shift is obtained by power spectrum analysis and weighted averaging method. Then get the fluid flow information in pipeline.4. Combined with simulation results and experimental measurements data, and demonstrated the effectiveness of this method. The results prove that: Studied the ultrasonic Doppler shift signal processing method can reduce the noise of the frequency shift signal and achieved the desired accuracy.