The Research Of Flow Measurement Technology Based On Ultrasonic

When ultrasonic transmits in fluid, it will carry on flow velocity information which ultrasonic flowmeter extracts to figure out the flow. The paper develops an ultrasonic flowmeter used to inspect the flow of blast-furnace circulating cooling water, in order to improve the current situation of flow measurement of blast-furnace circulating cooling water: high cost, cumbersome maintaining, numerous service parts, high technical requirements for workers.From the practical situation of blast-furnace cooling water, the paper determined systems solutions that the measurement principle adopts time difference method; sensors adopt U-shape installation; microcontroller adopts 32-bit ARM Cortex-M3 family Mono-Chip Computer STM32F103Re and accuracy achieves 1%. The paper researches and discourses the design and working process of ultrasonic sending and receiving circuit in detail. In circuit and PCB design, I specially consider the anti-interference technology, finally obtain the received signal of stable amplitude, low noise, clear waveform, which provides a good foundation for software design.In ultrasonic flow measurement based on time difference, The system accuracy mainly depends on the accuracy of time difference. This paper adopts the method which combines the high-speed timing with correlation algorithm to accurately measure time difference: The device starts timing at high-speed when excites ultrasonic, and stops the timing while amplitude of receiving signal is greater than the threshold level of comparator, and at the same time, it wakes-up high-speed ADC named AD9237 to collect receiving signal. After the collection of downstream and upstream, software algorithms calculate the correlation function to compensate the time difference measured by high-speed timing, and then has realized a precise measurement of time difference., Software also regulates the ultrasonic velocity varying with temperature of medium; and compensates the non-average velocity distribution, to ensure the accuracy of flow measurement.Profiting from above design of hardware and software, the ultrasonic flowmeter can be used to measure the flow of water when diameter is 30mm~1600mm, and flow is 1.27m3/h~150m3/h, can also be used to measure single-phase fluid's flow in other environments. This device has a CAN bus communication interface, therefore, we can use it to establish the field level flow meter within distributed control system.