The Research Of Water Level Tracking Open Channel Adaptive Flow Measurement System

Water resources is one of the most important issues in the world today.China has a vast territory,vast land and abundant resources,and the total amount of water resources is rich.However,the per capita occupancy is small,and there are differences in distribution between regions.China is also a large agricultural country,the proportion of agricultural water is relatively high,mainly reflected in the agricultural irrigation water,so it is very necessary to irrigate the area to measure water.The quantity of water in irrigated areas is an important measure to promote water-saving agriculture.In order to accurately measure the channel water flow,based on the current situation of flow measurement in open channel in irrigated areas of China,a set of water level tracking adaptive flow measurement system based on ultrasonic time difference method is designed.When the ultrasonic wave is propagating in the water,the flow speed of the water will lead to the difference in the propagation time of the ultrasonic wave in the upstream and the downstream.The velocity is obtained according to the time difference and then the open channel flow is obtained according to the velocity area method.The current measuring device mainly includes lead screw,stepper motor,ultrasonic probe,liquid level ultrasonic sensor,steering gear,slider,support rod,measuring rod,single side machine,display screen,power supply device,etc.The principle is that the ultrasonic level sensor at the top of the flow measuring device is used to measure the water level of the channel,and then the two ultrasonic probes at both ends of the measuring rod are used to calculate the velocity through the time difference between sound wave emission and reception.Finally,the formula AVQ(28)is used to measure the flow rate of the channel.According to the change of channel water level,the system automatically changes the position of ultrasonic probe under the drive of stepper motor and steering gear,and makes several measurements at different positions.Based on the principle of flow measurement and the analysis of experimental results,the device can meet the relevant requirements of flow measurement in open channel.This subject mainly carries on the following several aspects research.(1)The overall scheme of the system;According to the development history,present situation and characteristics of flow measurement in open channel in irrigated areas in China,based on the domestic and foreign literature of flow measurement in irrigated areas,combined with the principle of time difference method,ultrasonic sensor technology and automation technology,the overall scheme design of the flow measurement system is carried out according to the actual requirements.(2)Design and manufacture of flow measuring device;Flow measuring device is the key part of the system,including the design of mechanical structure,the selection of components,materials,installation and welding of components,etc.,to ensure that the flow measuring device in the optimal conditions,so as to ensure the flow measuring accuracy.(3)Hardware circuit design and software development of current measurement system;Carry on the microcomputer hardware circuit design.The hardware circuit design is the foundation to realize the flow measurement function.Complete the design of the main control circuit,the design of the power supply module,display module,the stepper motor drive unit,etc.;Write and debug software modules according to hardware circuit design.Software modules include software programming language design,user interface programming,man-machine interface programming,motion control function programming,information acquisition function programming.(4)Testing,analysis and optimization of hardware and software systems;The system function test of water level tracking open channel adaptive flow measurement system is divided into two stages.The second phase of testing is integration testing,which combines the various functions.Test whether the system can work properly and make continuous optimization and improvement.The experiment was carried out after the analysis and optimization.A large number of experimental data show that the current measurement system has high precision and basically meets the demand of flow measurement in open channel.The device is simple in structure,low in price,easy to carry,low in cost,high in precision,convenient in installation,and suitable for small and medium-sized standard rectangular channels.