Flow conditioning
(a) can be grouped into following three types – Straightening devices such as honeycombs and vanes inserted upstream of the flow meter can reduce the length of straight pipe required.
However, they produce only marginal improvements in measurement accuracy and may still require significant length of straight pipe, which a cramped installation site may not permit.
Such random inlet conditions would essentially simulate the realistic case in which air can enter the honeycomb from any direction and at any level of turbulence.
Top and bottom circular faces are considered as inlet to this domain to get a flow field with higher magnitude of lateral velocity.
This domain is provided with vertical and horizontal cylinders as an obstruction to the inlet to produce sufficient swirling at the exit of this section.
This figure shows the turbulence intensity and which is maximum at the center (30%) and at the walls is around 16-18%, now this profile is incorporated inside the honeycomb as shown in Fig.
This approach assumes that the selected technology does not exhibit any significant sensitivity to operating or mechanical variations between calibrations.
A proper manufacturer's experimental pattern locates sensitive regions to explore, measure and empirically adjust.
The manufacturer's recommended correlation method is a rational basis for performance prediction provided the physics do not change.
This approach assumes that the selected technology does not exhibit any significant sensitivity to operating or mechanical variations between calibrations.
(1) can be used to determine the flow profile's shape within the pipe by fitting a curve to experimentally measured velocity data.
In 1993, the transverse flow velocities were being measured within the high pressure natural gas environment using hot wire technology to accomplish the data fit.
A fully developed flow profile was used as the reference state for meter calibration and determination of Coefficient of Discharge (Cd).
Using the latest software technology a full pipe cross sectional description of the velocity profile is possible provided sufficient data points are given.
Hence this behavior was referred to the turbulence intensity of the gas flow that can cause metering bias error.
[8] Accurate standard compliant meter designs must therefore ensure that a swirl free, fully developed flow profile is impinging on the orifice plate.
The first installation option is to revert to no flow conditioning, but adequate pipe lengths must be provided by the eq.
[10] The individual results should be reviewed to ascertain details such as beta ratio, meter tube lengths, Re and test conditions.
Therefore, the latest findings regarding conventional tube bundle performance should be reviewed prior to meter station design and installation.
These devices generally are designed to rectify the drawbacks of the conventional tube bundle (accuracy and repeatability insufficiency).
The reader is cautioned to review the performance of the chosen perforated plate carefully prior to installation.
Accuracy is then ensured by completion of a calibration, indicating the relationship between rotational speed and volume, at various Reynolds Numbers.
Thus, one can manufacture an orifice meter of known uncertainty with only the measurement standard in hand and access to a machine shop.
Generally, recent research indicates that turbine meters are sensitive to swirl but not to the shape of the velocity profile.
Also, no significant errors are evident when installing single or dual rotor turbine meters downstream of two elbows out-of-plane without flow conditioning devices.
[12][13] Due to the relative age of the technology, it may be beneficial to discuss the operation of the multipath ultrasonic meter to illustrate the effects of flow profile distortion and swirl.
In case of a perfect fully developed real velocity profile of Ultrasonic meter which is shown in Fig.
There is a scarcity of theoretical models available to predict the errors reported by Coriolis meter in aforementioned conditions.
In single-phase conditions, Coriolis meter gives accurate measurement even in presence of severe flow disturbances.
These effects are mainly caused by debris on strainer screens, for various upstream piping geometries and different types of flow conditioners.
