抄録
Flow measurements with high accuracy for large pipings placed in power plants are difficult due to large Reynolds numbers. Large Reynolds number makes it difficult to determine the accurate flow correction factor for conventional flowmeters. Therefore, accuracy of flow rate measurements in conventional flowmeters such as flow nozzle flowmeter and electromagnetic flowmeter is questionable in large pipings in actual power plants. This paper presents experimental results for velocity-profile measurements using ultrasonic flowmeter applied for turbine condenser cooling water system in thermal plants, and steel penstock in hydraulic power plant. This piping is more than 1 meter in diameter, and Reynolds number is more than 1 million. As a result, velocity profile can be obtained by ultrasonic pulse Doppler flowmeter with small amount of miniaturized bubbles working as ultrasonic reflectors injected upstream of the measurement position.
