907 超音波流速分布計測法による水力発電所水車効率試験時における水圧鉄管内流速分布及び流量測定(2)(OS9-2 超音波を利用した流動場の計測(流量計測),OS9超音波を利用した流動場の計測,オーガナイズドセッション)

概要

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For appropriate plant management and operation, evaluation of water intake from a river is becoming more important at a hydroelectric power station. Time-of-fright ultrasonic flow-meters (TOP) are mainly used to measure the flow rate in a steel penstock during field efficiency test for hydraulic turbine at a hydroelectric power station. However, those flowrates measured by TOP may significantly differ from the actual flow rates if the flow remains undeveloped or axially asymmetric. As a plant is aging, inner surface of the steel penstock is getting rough, which will cause the change of velocity profile in a steel penstock. Recently, ultrasonic Doppler flow velocity profile measurement method (Udflow[○!R]) is being utilized, which directly can measure the flow velocity profile. Therefore, Udflow make it possible to obtain highly accurate flowrates even if flow is not in ideal condition. In this paper, velocity profile measurements using multiline system were conducted to obtain flow rates with a high degree of accuracy at the national standard loop. Then, we apply this method for the flow rate measurement of steel penstocks whose diameters are 1m-2m in actual hydroelectric power stations. Velocty profiles at different plant power outputs are obtained successfully using Udflow. Measurement results also showed good agreements in the comparison between TOP and Udflow in field efficiency test for hydraulic turbine.
2007-11-17