Vortex Meters
Vortex Meters, also know as vortex shedding flow meters or oscillatory flow meters, measure the vibrations of the downstream vortexes caused by a barrier in the moving stream.The vibrating frequency of the vortex shedding is related to the velocity of the flow.
Vortex meter works based on the principle of Karman vortex street. This principle essentially means that when an obstruction is placed in path of a flow , it can produce a series a vortices alternating from each side of the obstruction . The frequency of alternating of these vortices is proportional to the flow rate being obstructed. The vortex type meter uses a small rod called shredder bar or bluff bar to shred vortices from both sides in an alternating manner.Ultrasonic type transmitter and receivers are used downstream the shredder bar to send ultrasonic signals crossing the path of these vortices. These signals are used to measure the frequency of vortices for changing sides. These signals are sent to a software to be converted to fluid velocity and flow rate readings. Use of only a small shredder bar or bluff bar in the path of the flow, means very low pressure drop across the meter. It also allows high sensitivity of the readings at low flow rates, meaning large turn down ratios.