The Effect of Periodic Excitation on Orifice Plate Flow Meter Turbulence
Abstract
Inaccuracies in flow metering can be caused by the selective frequency response to pulsation of the large-scale structures naturally ocurring downstream of an orifice plate. To our knowledge, no previous published experimental research has included flow visualization and almost none of it considered the existence of large-scale structures. Some of the knowledge gained in other large-scale structure research is applied here to define regimes of nondimensional frequency where meter error is expected. Characteristic instabilities that have previously been found in shear layers, jets, and reattaching flows are shown to also exist in the orifice plate flow. Experimental results are presented from a test rig built exclusively to use smoke-wire flow visualization to study the physics leading to meter error. Pressures, velocities, and flow rate are measured to calculate the error in discharge coefficient corresponding to each photograph. A series of four pressure sensors are used to calculate the amplitude of pulsation at the orifice plate. The greatest meter error overpredicts the flow rate when the jet and reattaching flow structures are excited. This work was supported by NOVA Gas Transmission Ltd.
- Publication:
-
APS Division of Fluid Dynamics Meeting Abstracts
- Pub Date:
- November 1997
- Bibcode:
- 1997APS..DFD..Hc08S