Research On Measurement Method Of Water Suspended Sediment Concentration By Focused Ultrasonic

The suspended sediment content and characteristics of water are important parameters to characterize water quality.In recent years,the measurement of suspended sediment concentration in water is becoming more attractive area.Many aspects such as water conservancy and hydropower engineering construction,hydrological metering,water protection and hydrological observation and forecasting are needed to detect and monitor the sediment concentration and its characteristics.Nowadays,there are many kinds of measuring methods for the suspended-liquid two-phase flow.According to the measuring principle,it can be divided into direct measurement method based on traditional measurement method and indirect measurement method based on physics principle.Ultrasonic measurement method with its convenient,fast,has less effect to the fluid characteristics,long-term,on-line,uninterrupted measurement and other advantages and has been further research and application.This paper presents a method for measuring the concentration of suspended sediment in the water by the ultrasonic attenuation effect based on the focused transducer.Providing a new thinking for research on measuring the phase concentration and phase media distribution of the multiphase flow based on the ultrasonic.Mainly to complete the works are:(1)Present a method for measuring the concentration of suspended sediment in the water based on the focused ultrasonic transducer.A piezoelectric ultrasonic transducer with center frequency of 1.13 MHz was fabricated by using piezoelectric ceramic as the element material.Build a suspended sediment experiment parameter measurement equipment based on broadband focused ultrasound to carry out experimental study.(2)Carry out a series of experimental studies on the measurement of suspended sediment concentration.Establish a calibration system for the measurement of suspended sediment concentration.The water samples with different concentration and different diameter ratio were used to carry out ultrasonic test and to collect the feedback attenuation waveform.Using wavelet transform and Fourier transform method for signal processing.The wavelet transform with adaptive characteristics is used to reduce the noise.Determine the optimal decomposition level through the specific analysis and compare the wavelet denoising effect with the different size.Get the spectrum after the Fourier transform,which obtains the corresponding attenuation coefficient of the experimental conditions.(3)Establish the relationship between concentration and attenuation coefficient.The samples were divided into the different samples and the experiment was carried out.The effect of the diameter of the suspension on the attenuation coefficient was analyzed.The model for measuring the content of suspended particles in different particle sizes was established.The experimental data show that,the relationship between attenuation coefficient and concentration have a good power function among three different average particle sizes.In the experimental range,the average relative error is less than 2%,and the RMSE is less than 10%.The focusing transducer is combined with the established model,which has a good effect on the measurement of the suspended solids concentration in water under specific particle size conditions.