Larger Flowmeters Calibration

本研究利用聲波都卜勒流速儀(ADV, Acoustic Doppler Velocimeter)，於直潭淨水場進行流量量測以校驗其大型量水設施之流量計，以提高直潭淨水場出水量之準確性。對於實際量測後之流量推估計算方式，乃應用流速-面積原理之平均區域法及ADV所測得之流速資料加以推求。流速-面積原理中需各子斷面之面積與平均流速資料，而面積可由水深推算，各子斷面之平均流速則由流速分佈加以推算。根據校驗結果顯示直潭淨水場嚴重高估出水量，因此第一座之電磁流量計及第二座至第四座淨水池之文氏管流量校驗係數皆需重新調整。

The Acoustic Doppler Velocimeter (ADV) is applied in this study to take the velocities for determining the discharges in the open channels of the Chihtan Purification Plant. Then the discharges are used to calibrate the parameters of the larger flowmeters for accurate estimating the amount of water supply. In this study, the discgarge is determined by the mean-section method, which is the sum of the proudcts of the strip multiplied the mean velocity of the strip.Owing to the regular artificial flume, thearea can be easily determined by the water depth.The mean velocity of the strip is determined by the velocity distribution equation with the measured velocitiesat the vertical.The discharges obtained by the ADV and the flowmeters are used to calculate the coefficients for calibrating the flowmeters. Theresultes show the four larger flowmeters of the Chihtan Purification Plant over estimate the discharge.Thus all the flowmeters, including one magnetic flowmeter and the other three Venturimeters, are needed to be calibrated.