| 摘要 |
PURPOSE:To simplify the structure, to facilitate the design and to measure even gas, etc., having small concentration by providing a ultrasonic wave transmitting means and a means which detects an reflected ultrasonic wave on the basis of variation in load impedance in a vortex generator. CONSTITUTION:The ultrasonic wave transmitting means 7 which radiates an ultrasonic wave 6 to a vortex 3 continuously is formed in one body at the downstream side of the vortex generator. Then, an AC transmitting means 8, resistance R, processing circuit 9, and detecting circuit 10 are provided connecting with the means 7. When compressed fluid flows, the radiated ultrasonic wave 6 varies in density at the part of a vortex 3 and is reflected and the load impedance Z viewed from the side of the transmitting means 7 varies owing to variation in reflected wave sound pressure Pr. For purpose, amplitude modulation is imposed with the voltage eC at a connection point C. This signal is extracted as an envelope signal e0 through a processing circuit 9 and a detecting circuit 10 to detect the frequency of the vortex. |
