Research On Key Technology Of Hydrometry

Cableway box-hanging flow measuring method is one of the most widely used current measurement method,the cableway box-hanging flow measuring mainly accomplish the starting point,water depth and velocity data measurement.In the process of measuring the water depth,there are same problems,such as: the water surface signal and the underwater signal is inaccurate and unstable,the mechanical structure of the underwater signal triggering device is complex;When measure the velocity by rotating-element current meter,the signal is always influenced by the water resistance,resulting signal mining or leakage mining phenomenon,making the velocity measurement accuracy greatly reduced;In addition,the rotating-element current meter cannot automatically identify the flow rate signal according to changes of flow measuring environment,even it collects the flow rate signal,it cannot judge the signal that is accurate or not.Aiming at the problem of underwater signal acquisition in the process of sounding,using the ANSYS/LS-DYNA software establish the collision model of rod suspension the riverbed,and analysis the data of collision process,obtain the curve of the speed and acceleration,and deduce the change trend of the motor output torque at collision moment,comparing with the actual output torque of the motor,found that basically agreed,Finally,using the PLC program monitor the change of the feedback quantity of the servo unit,getting the underwater signal accurately.Analysis the structure and signal generation principle of different types of rotating-element current meter,and simulate different kinds of flow environment in the laboratory,measuring the resistance variation between the terminals rotating-element current meter,according to this situation design the hardware circuit of signal acquisition.Using the oscilloscope get voltage variation waveforms,getting the discipline of voltage variation while current meter on or off.According to this discipline design the signal collect scheme which treat the flow signal as analog signal.In the process of collecting flow signal with Arduino,firstly using the median filter to interfere the wave,then detecting the step change of the voltage value collect the flow rate signal.At the same time,according to the different resistance between air and water designed a new kind of surface signal acquisition method.Developed A hydrological data acquisition instrument which can automatically identify the velocity signal in different flow environment,and using the least squares method to collected the velocity signal automatically,and the error velocity signal can be realized in time,at the same time,conjunction with the photoelectric encoder can get the water depth.In addition,the instrument also has data storage,display and other functions,making the flow test more convenient and quickly.The solution of key technical problems when using the Cableway boxhanging,making the hydrometry is more efficient and the data is more accurate,which has had a positive effect on the popularization and application of the cable system.