The Effect of Flow Pulsations on Coriolis Mass Flow Meters

The Simulation of Coriolis Meter Response to Pulsating Flow Using a General Purpose F.E. Code

“…This can easily be deduced from the presence of two, independent, externally imposed time scales, namely the drive frequency and the pulsation frequency. A consequence of this di!erence is that an FE solution must either take a dynamic form, stepping forward in time until an asymptotic, fully developed motion is reached, with the sensor signal characteristics determined from temporal averages (at that condition), or the solution must be developed via a modal decomposition along similar lines to those used by Cheesewright and Clark (1998). It is not obvious, however, that the latter approach can be easily integrated with the applicability to complex geometries which characterizes modern general purpose FE codes.…”

“…The theoretical solutions reported by Cheesewright and Clark (1998) assumed that the meter was being driven with zero #ow and then the #ow (either steady or pulsating) was suddenly started. This would not have been easy to implement in the FE solution, so it was decided to start the transient solutions from a condition corresponding to steady #ow (at a velocity corresponding to the mean velocity of the pulsating #ow).…”

“…It should be noted that the derivation of equations (1) di!ers from the derivation of the equivalent equation given by Cheesewright and Clark (1998) in that it includes the e!ects of axial tensions, even though the tension does not appear explicitly in the equations [the tension has been eliminated by substitution from a force/momentum balance in the x-direction; see PamK doussis (1998) for details]. Closely similar equations can be written for the lateral displacement, the #exural rotation and the shear strain in the +x, z, plane.…”

“…They reported irregular meter output signals with pulsations at the drive frequency and large meter errors with pulsations at the Coriolis frequency. Cheesewright and Clark (1998) reported the results of an analytical solution to the problem, for a simple straight tube meter. This analysis suggested that, in the presence of #ow pulsations, the detector signals could contain components at four di!erent frequencies, namely, the drive frequency, the Coriolis frequency and frequencies corresponding to the sum and di!erence of the drive frequency and the pulsation frequency.…”

Silicon Straight Tube Fluid Density Sensor

“…Theoretical calculations show that the burst pressure for this sensor is in the order of 5 MPa corresponding to a maximum flow rate of 35 g s −1 for water. However, by ignoring expansion of the tube at high pressures, the resonance frequency of a straight tube is still slightly affected by the flow rate [15]. Theoretical calculations based on theories described in [15] show that for a water-filled tube, by passing the maximum flow rate through the tube, the resonance frequency changes only 0.5%, which is within the margin of error of the resonance frequency measurements.…”