| 摘要 |
PURPOSE:To improve the flow velocity measuring accuracy of an air current measuring instrument which measures the flow velocity of an air current to be measured in such a way that ultrasonic transmitters and receivers are arranged in the route of the air current and the flow velocity of the air current is measured with a measuring means based on the arrival time of ultrasonic waves at the receivers from the transmitters. CONSTITUTION:Transmitters a1 and a2 and receivers b1 and b2 are arranged so that the direction of the route L of ultrasonic waves connecting the transmitters a1 and a2 with the receivers b1 and b2 can coincides with the flowing direction of an air current Ax to be measured. In addition, an air blowing means is provided so as to blow air Ay upon the transmitters a1 and a2 and receivers b1 and b2 in the direction perpendicular to the route L at a velocity higher than the flow velocity of the air current Ax. |
