Investigation of two-phase horizontal stratified flow with pulsed laser velocimetry

Investigation of a two-phase, horizontal, stratified flow regime is being performed to determine the interface drag force and, correspondingly, the drag coefficient. The drag force is due to the relative motion between the two fluids at the interface. This drag force cannot be solved with analytical methods but can be experimentally determined. Interphase drag plays an important role in two-phase fluid regimes. The study of two-phase (and similarly two-component) flow regimes is necessary to properly understand and model complex fluid flows. Many computer codes that predict two-phase fluid flow must determine interphase drag force. Typically, a drag coefficient correlation is used that was empirically determined. One such code is RELAP5/MOD2. This code is used extensively in the nuclear power industry to simulate a wide range of steady-state, transient, and accident conditions in pressurized water reactors. Some researchers have found that thermal-hydraulic codes do not model constitutive two-phase flow relations very well. This deficiency has been attributed to an overprediction of the drag force, which may be caused by an inappropriate drag coefficient. Two-phase stratified flow information is being determined by the pulsed laser velocimetry (PLV) method. This technique is a full-field, two-dimensional, noninvasive flow visualization technique. Many investigators have utilized this and similar imaging techniques to obtain full-field velocity measurements