ABSTRACT
Three primary metering principles, vortex, vortex swirl (precession), and the Coanda effect, are examined in this chapter. In all three, the primary device generates an oscillatory motion of the fluid whose frequency is detected by a secondary measuring device to produce an output signal that is proportional to fluid velocity.
The main focus is on the vortex meter which enjoys considerable success in the field of steam metering. This chapter concentrates on the formation of vortices and the influence of the shedder design on the Strouhal factor and subsequent linearity.
After reviewing various sensor designs, we take a look at a number of applications and the limitations of the technology due to the requirement for a minimum Reynolds number.
Next we look at the working principle of the vortex precession meter and how its low susceptibility to the flow profile requires only three diameters of straight line upstream of the meter.
Finally, we examined how the Coanda effect is harnessed in the fluidic flowmeter to provide a metering system able to be used with fairly viscous media.
