FLOWMETER BASED ON THE VORTEX FLOW MEASUREMENT PRINCIPLE

摘要

A flow measuring device operating on the vortex counter principle, comprises: a measuring tube; a blockage in the form of a bluff body in the measuring tube for bringing about a Karman vortex street with flow dependent vortex frequency; a first pressure fluctuation measuring arrangement for registering vortex related pressure fluctuations and for providing signals dependent on pressure fluctuations; a second pressure fluctuation measuring arrangement for registering vortex related pressure fluctuations and for providing signals dependent on pressure fluctuations. The first pressure fluctuation measuring arrangement is spaced in the longitudinal direction of the measuring tube from the second pressure fluctuation measuring arrangement. An evaluating unit for determining a vortex frequency and a flow measured value dependent thereon, and the evaluation unit is further adapted, based on the ratio of the amplitudes of the signals of the first pressure fluctuation measuring arrangement and the second pressure fluctuation measuring arrangement, or variables derived therefrom, to determine the current Reynolds number and/or the kinematic viscosity of the medium flowing in the measuring tube.