Patent ID: 6351999
Filing Date: 2002-03-05
Classification: G01F,G01N

Abstract:
A vortex flow sensor for measuring at least one of the flow velocity and the volumetric flow rate of a fluid, said vortex sensor comprising;a measuring tube; through which the fluid flows in a first direction and which has a wall in which a first window and a second window of optical, schlieren-free, high temperature glass are set fluid tight and pressure tight at points lying opposite each other along a first diameter of the measuring tube; a bluff body disposed along a second diameter of the measuring tube and fixed in the measuring tube for generating KÃ¡rmÃ¡n vortices in the fluid, whose frequency is proportional to the flow velocity, said second diameter lying upstream of, and being essentially perpendicular to, the first diameter; and a laser differential interferometer having a transmitting unit mounted outside the measuring tube in front of the first window and fixed to at least one of the first window and the measuring tube, said transmitting unit comprising the following optical components, which follow one another in the direction to the first window; a laser, a lens system, a first polarization filter, a first Wollaston prism, and a first lens, and a receiving unit mounted outside the measuring tube in front of the second window and fixed to at least one of the second window and the measuring tube, said receiving unit comprising the following optical components, which follow one another in a direction away from the second window; a second lens, a second Wollaston prism, a second polarization filter, and a PIN diode.