| 摘要 |
A method and appartus for measuring volumetric flow through a duct without knowing the viscosity of the fluid is provided. A dual rotor turbine volumetric flow meter is operably connected to a duct having fluid flowing therethrough. The dual rotor turbine has a temperature gauge, a first rotor and a second rotor with at least one of said first rotor and said second rotor having a non-linear response to fluid flow. The dual rotor turbine volumetric flow meter is calibrated by deriving a Roshko/Strouhal number curve therefor. During measurement, a first rotor frequency and a second rotor frequency are determined. The second rotor frequency is divided by the first rotor frequency to derive a frequency ratio which is then used to calculate a combined Roshko number. A combined Strouhal number is derived by using the combined Roshko number in conjunction with the Roshko/Strouhal number curve. The volumetric flow rate is calculated using the combined Strouhal number.
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