Patent ID: 6220103
Filing Date: 2001-04-24
Classification: G01F

Abstract:
Vortex detector apparatus for detecting vortices produced by a bluff body positioned in a stream of flowing fluid at vortex frequencies that are indicative of flow velocity of the flowing fluid, comprising:a vane positioned immediately downstream from said bluff body, said vane having solid, elongated body with a proximal end and a distal end such that a longitudinal vane axis extends through said proximal end and through said distal end, said solid, elongated body having a pair of lateral sides that extend from the proximal end to the distal end on respectively opposite sides of the longitudinal vane axis, each of said sides having a leading edge that is upstream from the longitudinal vane axis and a trailing edge that is downstream from the longitudinal vane axis and both of said lateral sides converging toward each other from their leading edges to their trailing edges, and said solid elongated vane having a front face that extends between said leading edges from said proximal end to said distal end;a cantilevered joint at said proximal end of said vane connecting said vane to a stationary stem such that said proximal end of said vane is restrained by said cantilevered joint while said distal end of said vane is unrestrained by anything other than the vane, said cantilevered joint including a hollow neck formed by a shank with a cylindrical wall that is coaxial with said longitudinal vane axis and extends axially between said proximal end of said vane and said steam in said stream of flowing fluid, a first web positioned upstream from the shank and extending between said proximal end of said vane and said stem, and a second web positioned downstream from the shank and extending between said proximal end of said vane and said stem, said hollow shank, first web, and second web being a less in combined total cross sectional area than either the stem or the elongated body, wherein said vane including said elongated body, hollow shank, first web and second web comprise a unitary structure of plastic having a modulus of elasticity in the range of about 1.times.10.sup.5 to 5.times.10.sup.6 p.s.i. and a resonant frequency that is significantly higher than said vortex frequencies; anda pair of strain gauges positioned and potted inside the neck formed by said hollow shank and disposed adjacent diametrically opposite sides of said cylindrical wall and on opposite sides of a plane that includes aid longitudinal vane axis and that extend through both said first web and said second web in such a manner that said strain gauges produce electric signals that are indicative of strain magnitudes in said respective diametrically opposite sides of said cylindrical wall.