Notes on Calculated Quantities

The majority of the measurements are direct measurements, but for convenience, some calculated quantities are also given. The most important are these:

• USG, USO, USW: Superficial velocity
• DPDX: Pressure gradient
• H: Liquid hold-up
• RHO_MIX: Mixture density

It is possible to recalculate these quantities based on the raw data (except for superficial velocities), but this will require very careful study of the configuration as described in the accompanying reports.

Superficial velocities are based on measurements of volumetric or mass flow rate. As pressure and temperature change from the point of measurement, these measurements are adjusted for density changes. The calculated velocities will be representative of a point given by the location parameter, and usually, the general pressure (P) and temperature (T) will be referenced to the same location.

Pressure gradient estimates are based on a number of pressure measurements along the test section or direct pressure difference measurement. Not all available measurements may be used for the estimate because some will typically be excluded due to inlet or outlet effects.

Hold-up is in most cases measured using gamma radiation-based density measurements. In many cases, it is assumed that the fluids are distributed stratified in the transverse direction, but for more recent data, the measurement may be a true hold-up measurement.

Mixture density is calculated based on phase densities and hold-up measurement. This density is useful for calculating flow friction and Reynolds' number.