Method and apparatus for measuring the velocity of liquid flowing in a moving stream

摘要

The measurement involves emitting acoustic signal having selected frequency into a liquid (14) flowing in a stream. Acoustic signals reflected by solid particles (16) moving with the liquid in the stream are detected. The Doppler frequencies of the reflected signals (22) are determined. A spectrum of amplitude versus Doppler frequency is produced. A trend line is generated to fit the amplitude values at the high frequency end of the Doppler frequency spectrum. The intercept of the trend line with the zero amplitude axis is determined to produce a value representing the maximum velocity of the moving liquid in the stream.