| 摘要 |
PURPOSE:To accomplish higher reliability of fluid flow velocity measurement using the value independent of the objective measurement value as the reference value in the measurement of the fluid flow velocity employing acoustic wave including supersonic wave. CONSTITUTION:Acoustic wave is received or transmitted in the opposite direction to each other between transmitting devices 1 and 2 and receiving devices 3 and 4 are separated at a fixed space L as opposed to each other to detect the propagation times t1 and t2 of each acoustic wave in the opposite direction. The value, T=(t1+ t2)/t1t2, is computed to be memorized in the comparison value memory circuit 10 as comparison standard value T0. At the same time, from the propagation times t1 and t2, the value corresponding to the fluid flow velocity, wind speed, vector Vx is determined by computing the equation of [(t2-t1)/t1t2]L/2 and memorized so temporarily in the register 7 to allow continuous output. The value T is used as the noise decision value. When the noise decision value obtained at a certain cycle with respect to the T0 exceeds the allowable range succesively at N cycles, the comparison standard value is corrected adopting the noise decision value T at the cycle N as the new comparison standard value T0. Thus, highly reliable fluid flow velocity measurement can be done. |
