Swirl flow meters (vortex precession)

• The swirl meter is based on the principle known as vortex precession.
• The swirl meter can be used with both gases and liquids, its main application as a gas flow meter.
• The major advantage of the vortex precision technique over that of vortex shedding is, only three diameter of straight line required upstream of the meter (3D/1D)
• A inlet guide body whose shape is similar to a stationary turbine rotor is located in the inlet of the measuring device.
• The fluid entering the meter to spin about the center line this swirling flow passes through a venture, where it is accelerated and then expanded in an expansion chamber.
• The expansion changes the direction of the axis about which the swirl is spinning- moving the axis from a straight to a helical path. This spiraling vortex is called vortex precision.
• A flow straighter is used at the outlet from the meter.
• The rotation (swirl) is measured with pizeo sensor.
• The vortex shedding frequency is between 1 and 2000Hz, the higher.