Design Of Multi-path Ultrasonic Flowmeter With Experimental Research

Flow and temperature, pressure are the most three important measurements in the process industry. With the development of "West to east gas pipeline project", the construction of the city gas pipeline, the implementation of the civil oil and the natural gas commercial policy, the measurement of the chemical production control of material flow and the increase of the water supply pipeline project, the flowmeter gets more and more attentions and has an irreplaceable role in the development of the national economy. The ultrasonic flow measurement technique uses the ultrasonic signal which contains the fluid velocity information to measure the fluid velocity. The advantages of this novel technique are high-precision, well low velocity, low pressure loss, wide application, wide measuring range and so on. This topic designs a kind of low-power multi-path ultrasonic flowmeter based on STM32 L which is an embedded ARM Cortex-M3 CPU. The main works of this paper are summarized as follows:(1)According to the research status at home and abroad, this paper analyzes the ultrasonic propagation characteristics in the medium and studies the working principle of the ultrasonic transducer. In addition, this paper analyzes the principle of the different types of the ultrasonic flowmeter in details, and compares their advantages and disadvantages, distinguishes their applicable occasions. Finally, according to the design requirements, we propose that use the time-difference method to design the ultrasonic flowmeter.(2)On the premise of low-power requirements, a design scheme of the ultrasonic flowmeter, based on STM32 L and TDC-GP22, is proposed. This paper also proposes an overall design scheme of hardware circuit of the multi-path ultrasonic flowmeter. Based on the technical requirements of every module, we select the suitable chip, design the circuit and apply anti-interference measures to reduce the interference. In addition, this system uses multi-path echo signal automatic gain control and error correction algorithm to improve the measurement precision and realize the high precision measurement, data storage and online monitoring of liquid flow rate. The advantages of this system are high measuring accuracy, strong scalability, optional of the medium and the number of the channel and low-power consumption.(3)By using the modularized software design method, the whole system contains program module, time measuring module, data processing module and the key processing module, etc. In addition, we propose the overall flow chart of the software design, and design the time measuring program, the interrupt program and the multichannel measuring calculation, respectively, so as to realize the control of normal work of the whole hardware system and realize the data processing, display and other functions.(4)Based on the design of the hardware circuit and the software control process, we set up the experimental platform and test the multi-path ultrasonic flowmeter by the experiment. By analyzing the results of the experiment, the validity and the feasibility of the multi-path ultrasonic flowmeter in this paper are verified and validated. Furthermore, it is proven that the design scheme has higher measuring accuracy.