Vortex Flowmeter working Principle

Vortex Flowmeter working Principle

Non-streamline vortex-maker be set in fluid (anti-flow part),then two regular vortex would be come out ,from two sides of the vortex-maker in turn,so this kind of vortex be called as Karman vortex flow meter，Chart I as follow.

                                chart I

Vortex is not flowing symmetrically under vortex-maker set .As if, set frequency of vortex is f，the speed of test medium is V,inlet face width of vortex-maker is d,Past part diameter is D,as the principle of Karman vortex flow meter,as follow:

                         f=StV/d                 I

Factor:

f－The Karman vortex flow meter frequency which one side of vortex-maker

St－Strouhal number(dimensionless number)

V－mean flow rate

d－the width of vortex-maker

So,check the separate frequency of Karman vortex flow meter to know the instant capacity(flow) .among, Strouhal number(St) is dimensionless number,

Chart II Show the relation of, Strouhal number(St) & Reynolds number (Re)

Straightness part in curve(St=0.17),free frequency & flow rate of vortex is direct ratio, it means flow sensor range. so just check out frequency (f),we can get the flow rate inside pipe, then as the flow rate(V) to take volume flow, the ratio record of impulse & volume, called as(K),as follow (2)

　                       K＝N/Q(1/m³)         (2)

Model:K＝instrument constant (1/m³)

N＝impulse number

Q＝volume flow (m³)