METHOD AND DEVICE FOR MEASUREMENT OF FLOW RATE Russian patent published in 2001 - IPC

FIELD: measurement technology; optical meters of liquid or gas flow velocity; measurement of velocity and direction of wind; measurement of flow rate in pipe lines; measurement of velocities of ultra-pure substances since presence of diffusing particles in flow is not required. SUBSTANCE: specific feature of proposed method consists in recording spatial deviation of laser radiation beam passing the medium under test by fluctuations of refractive index of medium. To this end, opposite boundary parts of beam are detected only by part of light-sensitive areas of two or more photodetectors. Output signals of detectors are amplified in anti-phase and cross-correlation function of these signals is computed which is used for finding the velocity being measured. To enhanced accuracy of measurement, fluctuations are increased by heating the medium under test (periodic heating inclusive) near volume being measured. At regular heating, signal of detectors are amplified selectively at heating frequency. EFFECT: simplified construction of device; extended field of application. 8 cl, 3 dwg