Installation effects on an ultrasonic flow meter with implications for self diagnostics

Abstract

A small ultrasonic flow meter for water was exposed to five different test configurations, a reference experiment, a single elbow, a double elbow out of plane, a reduction in pipe diameter and a pulsating flow experiment. All tests were performed in a flow calibration facility ranging over Reynolds number from 25 to 110 000. The experiments with the four installation effects were compared with a reference experiment. The error and the change in standard deviation compared to the reference experiment were calculated. The standard deviation serve as a measure of the noise level of the flow meter. The results show that all disturbances generated errors in the flow measurement. The maximum errors were mainly in the range of 2-4% of flow rate, but at very low flow rates the pulsating flow caused larger errors. In most of the flow range there were no or smaller errors. All installation effects also generated an increase in the noise level. The different pipe configurations increased the standard deviation up to more than 100%. The pulsating flow induced even higher enlargements in the noise level. The errors and the increase in the standard deviation are present in about the same flow ranges. The results demonstrate not only that the installation effects tested introduce errors in the flow measurements but also that these effects can be detected from the noise level in the data. The noise level was determined from the standard deviation. This could be interpreted as that the disturbances amplify the turbulence intensity. Thus the standard deviation can be used as a measure of the turbulence. The presence of a disturbance could be recognised by comparing the magnitude of the noise level in the present data with a reference level valid for the measured flow rate. A procedure like this could possibly be performed by the meter itself in operation.

On the effect of the mounting angle on single-path transit-time ultrasonic flow measurement of flare gas: a numerical analysis

“…(15) was below approximately 0.15, justifying therefore the choice of the RNG K − model. Additionally, the RNG K − model also requires less computational effort than the (13)…”

“…The authors use Laser Doppler Anemometry (LDA) to recover complete information on the velocity components of disturbed profiles. Carlander and Delsing [13] performed a series of experiments comparing the standard deviation of ultrasonic flow measurements under disturbed condition against a reference condition. The authors found that, depending on the disturbance, the standard deviation can increase by up to more than 100%.…”

A Survey on flow meters based on application

“…On the other hand, when there is flow of fluid in the pipe, the frequency of the reflected wave will be different. This is because of phenomena called as Doppler Effect [36]. The faster the fluid flows, the frequency shift will increases linearly.…”

Reproducibility of Experiments With Swirling Flow: Numerical Prediction With Polynomial Chaos

“…However, swirling flow may also be a spurious effect, for example in flow measurement applications where an undisturbed fully developed flow profile may be favorable to achieve a small measurement error and good repeatability. Flow sensors are commonly tested with swirling flow conditions to assess their robustness (see, for example, Carlander and Delsing [1] and Wendt [2]). In such experiments, the flow patterns introduced by disturbance generators emulate flow disturbances caused by installation effects often found in pipe configurations, such as bends, junctions, and valves.…”

“…There are two main difficulties in investigating the reproducibility experimentally: (1) In practice, it is difficult to separate reproducibility contributions from the swirling flow field from intrinsic reproducibility contributions of the flow sensor under test and (2) to reliably assess reproducibility of such tests, a large set of experiments would be required.…”