Design Of Fluid Multiparameter Ultrasonic Measuring Instrument

Fluid parameters include volume flow,density,mass flow,etc… These parameters are usually accurately measured in experimental research and industrial production.The precision of traditional measuring instruments is generally not high.With the development of measurement technology,ultrasonic technology has been widely used in the measurement of fluid parameters due to its high measurement accuracy and wide range of measurements.However,ultrasonic technology is rarely used to study the multiparameter measurement of fluids.Based on this,a fluid multiparameter ultrasonic measuring instrument is designed,and a method of measuring fluid volume flow,density,and mass flow at the same time using ultrasonic technology is proposed,which provides a possibility for an instrument to measure multiple parameters.The theoretical basis of the fluid multiparameter ultrasonic measuring instrument is the time difference method,which indirectly realizes the multiparameter measurement by using the relationship between the wave propagation time in the fluid medium and the volume flow,density,and mass flow values.This paper analyzes the measurement principle of flow,density and mass flow in detail,and completes the design of the fluid multiparameter ultrasonic measuring instrument,including the installation of ultrasonic transducer,the generation and reception of ultrasonic signals,and the analysis and processing of echo signals.The hardware part of the fluid multiparameter ultrasonic measuring instrument is based on FPGA.The main functions realized are: controlling DDS chips to generate ultrasonic driving signals;Combined with the D/A conversion circuit to collect echo signals at high speed and store them in RAM memory in FPGA;The NIOS_II processor is built on the FPGA chip to implement the control of each module and analyze and process the data in memory.The software part designs temperature measurement algorithm,signal acquisition algorithm,software subdivision interpolation algorithm and maximum feature wave search algorithm.The temperature measurement algorithm is designed to obtain the temperature of the fluid and compensate the measurement results.The echo data are sampled at high speed by signal acquisition algorithm.Thecharacteristic wave search algorithm is used to compare the sample data in the memory RAM to find the characteristic wave.The end time of ultrasonic wave is calculated by software segmentation interpolation algorithm.In the experimental part,the design scheme of multiparameter ultrasonic measuring instrument is demonstrated by using pure water as fluid medium.At the same time,the relationship between temperature and propagation time is verified by experiments.The results show that the measurement error of ultrasonic propagation time is better than nanosecond level.It can effectively detect fluid flow rate,volume flow rate,density,and mass flow rate.It provides theoretical basis and technical support for the development of fluid multiparameter ultrasonic measuring instrument.