초록 ▼

A Doppler flowmeter impulses an ultrasonic fixed-frequency signal obliquely into a slurry flowing in a pipe and a reflected signal is detected after having been scattered off of the slurry particles, whereby the shift in frequencies between the signals is proportional to the slurry velocity and henc

A Doppler flowmeter impulses an ultrasonic fixed-frequency signal obliquely into a slurry flowing in a pipe and a reflected signal is detected after having been scattered off of the slurry particles, whereby the shift in frequencies between the signals is proportional to the slurry velocity and hence slurry flow rate. This flowmeter filters the Doppler frequency-shift signal, compares the filtered and unfiltered shift signals in a divider to obtain a ratio, and then further compares this ratio against a preset fractional ratio. The flowmeter utilizes a voltage-to-frequency convertor to generate a pulsed signal having a determinable rate of repetition precisely proportional to the divergence of the ratios. The pulsed signal serves as the input control for a frequency-controlled low-pass filter, which provides thereby that the cutoff frequency of the filtered signal is known. The flowmeter provides a feedback control by minimizing the divergence. With the cutoff frequency and preset fractional ratio known, the slurry velocity and hence flow will also be determinable.

대표청구항 ▼

A method of determining the velocity of a slurry flowing in a pipe, comprising the steps of radiating a fixed-frequency ultrasonic signal obliquely into the pipe toward its center and receiving off the flowing slurry a scattered signal that is varied according to the slurry flow and combining the fi

A method of determining the velocity of a slurry flowing in a pipe, comprising the steps of radiating a fixed-frequency ultrasonic signal obliquely into the pipe toward its center and receiving off the flowing slurry a scattered signal that is varied according to the slurry flow and combining the fixed-frequency and scattered signals to give a Doppler shift signal, filtering the Doppler shift signal off the high frequency end and comparing the filtered signal against the Doppler shift signal to obtain a fractional ratio signal, comparing the fractional ratio signal against a preset fractional ratio signal and minimizing the divergence of the fractional ratio signals in a feedback loop, and determining from the feedback loop and the present fraction ratio signal the bandwidth frequencies of the filtered and the Doppler shift signals, which bandwidth frequencies are proportional to and can be used to determine the velocity of the slurry flow.