Crossed beam ultrasonic flowmeter

A crossed beam ultrasonic flowmeter comprising:

• A. first, second, third and fourth ultrasonic beam transmitting transducers disposed generally equiangularly and numerically consecutively about an axis;
• B. continuous wave signal generating means connected in circuit relation to said transducers for driving said transducers at predetermined frequencies, the difference between the frequencies of said first and third transducers differing from the difference between the frequencies of said second and fourth transducers;
• C. focusing means connected to said transducers for focusing the beams thereof to intersect in a predetermined region along said axis through which region dynamic particles undergoing velocity analysis are moving, said transmitting transducers being disposed about said axis on one side of said region;
• D. a receiving transducer disposed adjacent said axis intermediate said beams of said transmitting transducers for receiving the ultrasonic signal scattered from dynamic particles undergoing velocity analysis;
• E. heterodyning means connected in circuit relation to said receiving means for squaring the ultrasonic signal received from said receiving means;
• F. filter means connected in circuit relation to said heterodyning means operable to separate the spectrally separated scattered ultrasonic signals resulting from said first and third, and said second and fourth transducers;
• and
• G. spectrum analysis means connected in circuit relation to said filter means for analyzing said scattered ultrasonic signals.

A method for measuring the velocity of a dynamic particle wherein the steps comprise:

• A. mounting first, second, third and fourth transducer means in spaced relation and numerically consecutively about an axis;
• B. energizing said first and third transducer means to propagate a first pair of continuous wave ultrasonic beams having different frequencies;
• C. energizing said second and fourth transducer means to propagate a second pair of continuous wave ultrasonic beams having different frequencies with the difference in frequencies between said first pair of transducer means differing from the difference in frequencies between said second pair of transducer means;
• D. focusing said beams of said transducer means to intersect in a predetermined region along said axis through which dynamic particles undergoing velocity analysis are moving, the focused beams of said first and third transducer means and said second and fourth transducer means defining a pair of planes intersecting at a predetermined angle;
• E. detecting, heterodyning, and filtering the ultrasonic signal scattered from dynamic particles undergoing velocity analysis to separate the spectrally separated scattered signal resulting from said first and third, and said second and fourth transducer means;
• F. de-energizing said first transducer means to terminate the beam generated thereby whereby said first transducer means functions as an ultrasonic receiver;
• G. detecting with said first transducer means the ultrasonic signal scattered from dynamic particles undergoing velocity analysis;
• H. filtering said ultrasonic signal to separate the spectrally separated scattered ultrasonic signal resulting from said third transducer means;
• and
• I. analyzing the spectrum of the filtered ultrasonic signal to obtain the desired frequency information.

A crossed beam ultrasonic flowmeter comprising:

• A. at least one pair of cooperating, spaced ultrasonic beam transmitting means, each of said ultrasonic beam transmitting means being comprised of a multiplicity of separate transducing elements arranged in a predetermined array;
• B. signal generating means connected in circuit relation to said transmitting means for driving one transmitting means of the pair at a first ultrasonic frequency and the other transmitting means of the pair at a second ultrasonic frequency;
• C. electronic focusing means connected to the several transducing elements of each of said transmitting means for focusing the beams of said transmitting means to intersect in a predetermined region through which dynamic particles undergoing velocity analysis are moving and to limit the ultrasonic volume in the predetermined region;
• D. receiving means for receiving the ultrasonic signal scattered from dynamic particles undergoing velocity analysis;
• E. filter means connected in circuit relation to said receiving means for separating the scattered ultrasonic signal received from said receiving means;
• and
• F. spectrum analysis means connected in circuit relation to said filter means for analyzing said scattered ultrasonic signal.