Research On The Method Of Enhancing The Accuracy Of Small-caliber Civil Ultrasonic Water Meters

Measurement accuracy is the key barrier in the research and development of ultrasonic electronic water meter.Due to the fact the ultrasonic wave has a short travel distance and is pro to influential factors such as external sound waves or fluid vibrations,significant randomized errors arise as a result.Such error is more pronounced at small flow points.This dissertation uses the differential time to calculate the flow rate of water.The aim is to increase the accuracy of the civilian small-diameter ultrasonic electronic water meter.It critically analysis variables that could potentially influence the accuracy,to propose methods to effectively avoid or solve such problems,covers both the hardware design and the software development.(1)Taking into account the accuracy of differential time acquisition,this dissertation uses the E703.15 ASIC single-chip with a time resolution of 38 ps to ensure the accuracy of the time;the dual threshold system constantly controls to ensure a precise capture of the ultrasonic signal onset time and accurately measures the ultrasonic propagation time.(2)The zero flow differential time is a significant influential variable on the measurement accuracy for both the small flow and large flow.However,the impact is relatively minor when comparing the measurement accuracy for large flow than for small flow.Using Kalman filter to estimate the zero flow differential time,smooth the data and eliminate the pulse interference,greatly reduce the measurement error of the small flow and improve the stability of the measurement error.(3)Due to the variation of different pipes water flow through,the water flow velocity can be significantly impacted,which results in uneven flow velocity distribution and measurement error.In addition,water flow can also be disturbed due to the reflection column in the pipe,as a result modeling the flow velocity of the fluid mechanics is complicated.This paper uses the sub-basin linear compensation sound velocity method to correct the water velocity,and achieve a good measurement effect.During the scientific experimental process,this research also found that temperature has a significant influence on the water flow velocity.The research uses temperature-subdivision sub-watershed linear sound velocity to effectively compensate and solve the measurement error caused by temperature changes.(4)Due to the necessity of perform sound velocity compensation for temperature in different sections,in order to determine the compensation values for temperature andsound velocity,this dissertation introduces the calibration system and upper computer.This system enable direct observation of the water metering volume,instantaneous flow rate,and its changing status.Researchers can calibrate the flow rate curve and perform zero-flow differential time estimation to facilitate the observation of the water meter status and calibration accuracy.This dissertation reviews the parameters in the measurement formula.The influential factors for the lower measurement accuracy were critically analyzed and solutions were proposed.The scientific experiment conducted in this research demonstrate satisfied result by using the proposed methods to improve the measurement accuracy of small-caliber civilian ultrasonic water meters.The result measurement accuracy fully meets the national standards for secondary water meter.