Patent ID: 6692535
Filing Date: 2004-02-17
Classification: G01F

Abstract:
A method of measuring volumetric flow through a duct without knowing the viscosity of the fluid, the method comprising the steps of:providing a dual rotor turbine volumetric flow meter connected to a duct having fluid flowing therethrough, the dual rotor turbine having a temperature gauge, a first rotor and a second rotor, at least one of said first rotor and said second rotor having a non-linear response to fluid flow, calibrating the dual rotor turbine volumetric flow meter by deriving a Roshko/Strouhal number curve therefor, determining a first rotor frequency and a second rotor frequency, dividing the second rotor frequency by the first rotor frequency to derive a frequency ratio, calculating a combined Roshko number using the frequency ratio, determining a combined Strouhal number using the combined Roshko number and the combined Roshko/Strouhal number curve, calculating the volumetric flow rate using the combined Strouhal number.