| 摘要 |
PURPOSE:To effectively and exactly execute the flaw detection in a tube by providing an acoustic mirror which is connected to the downflow side through a hollow shaft and reflects an ultrasonic wave in the tube axis direction to the tube diameter direction, on a turbine supported in a cylindrical casing. CONSTITUTION:While moving a casing 2 in the tube axis direction of a tube 1 to be inspected at a suitable speed, water 10 is allowed to flow into the tube 1, and an ultrasonic wave 11 is emitted from an axial direction ultrasonic probe 9. As for the water 10 flowing in the casing 2, its flow velocity is increased by a draining jig 8, this flow velocity hits against a turbine blade, and a water turbine 5 rotates. As a result, an acoustic mirror 6 fixed to the downstream end of a hollow shaft 4 rotates at the same speed, and the ultrasonic wave 11 propagated in the tube axis direction in the shaft 4 hits against the reflecting surface of the mirror 6 and reflected in the tube axis direction of the whole periphery. The reflected ultrasonic wave 11 is propagated to the tube 1 and reflected with information in its wall thickness, and this reflected wave is received by the probe 9 again, and transmitted to an ultrasonic flaw detector. In such a way, the ultrasonic wave 11 scans helically the whole periphery of the tube 1 extending over the overall length and executes a flaw detection. |
