What is the Bernoulli
Principle and how does it affect the Precision Turbine Flowmeter?
With axial thrust forcing the precision turbine meter
(PTF) rotor downstream, friction resulting from contact between the rotor and the
downstream cone would cause excessive wear if there were not some means of balancing or
"floating" the rotor on its axis between the upstream and the downstream cones.
Bernoullis Principle states that when flow velocity decreases, the
static pressure increases. Therefore, a high-pressure area exists at the downstream side
of the PTF rotor, exerting an upstream force on the rotor. As a result, the rotor is
hydraulically balanced on its axis as demonstrated in Figure 1, essentially
"floating" between the cones. As a result of the ENHANCED FLOATING ROTOR (EFR)
design of the PTF, requirements for downstream thrust bearings are eliminated because the
rotor does not rest against any surface when operating in its linear range.