Numerical investigation of cavitating Herschel Venturi-Tubes applied to liquid flow metering

• Cavitating Herschel Venturi-Tubes are applied to liquid flow metering, showing a very stable mass flow rate.
• The behaviour itself shows analogies to the critical flow Venturi nozzles (CFVN) known from gas metering.
• The geometry at the cavitation inception region has been identified as a crucial part for a stable mass flow rate.
• For vapour cavities long enough, a possible unsteady cavity movement does not interact with the mass flow at the throat.

The objective of the present work is the numerical investigation of the applicability of hydrodynamic cavitating Herschel Venturi-Tubes to liquid flow metering. For this purpose, two- and three-dimensional simulations of cavitating flow in two different nozzle geometries were carried out using commercial CFD code. For several reasons, the Herschel Venturi-Tube proved to be superior to other types of nozzles such as the ISO 9300 with respect to liquid flow metering.