Vortex Flowmeter

used for measuring flow of industrial pipeline fluid, little pressure loss, broad span range and high accuracy

OPERATION PRINCIPLES

Setting vortex generation body (bluff body) in fluid, regular vortexs will alternately generate from two sides of vortex generation body. This kind of vortex is called Karman vortex. See picture 1. Vortex is at downstream of vortex generation body, unsymmetrical array. Set occurrence to be f , avarage flow speed of measured medium U, face width d and diameter D. According to Karman principle, exsiting following relation :

 f = StU1/d = StU/md

U1 - avarage flow speed at two sides of vortex generation body, m/s

St - Strouhal number

m – ratio of segment area and pipeline cross sectional area

In the formula K --- Instrument Coefficient, pulse number/m3 (P/m3)

K has relation with vortex generation body, pipeline dimension and Strouhal nember. Strouhal nember is a parameter without dimension. It has something to do with shape of vortex generation body and reynolds number. Seeing from the picture, in the range of Re = 2 * 104 ~ 7 * 106, St can be seen to be a constant. When measuring gas flow, flow calculation formula of HLUG is

Vortex Flowmeter