Fluid flow through a vertical to horizontal 90° elbow bend III three phase flow

Three phase water/oil/air flow was studied around a vertical upward to horizontal 90 degrees elbow bend of R/d = 0.654. The results were more complex than corresponding two phase data. The pressure drop recorded for the two tangent legs sometimes showed significant variations to the straight pipe data. In most cases this variation was caused by differences in the flow regimes between the two systems. The elbow bend tended to constrict the flow presented by the vertical inlet tangent leg while sometimes acting as a wave and droplet generator for the horizontal outlet tangent leg. It could be argued that the inclusion of the elbow bend altered the flow regime map transitional boundaries but it also is possible that insufficient settling length was provided in the apparatus design. The elbow bend pressure drop was best presented as l(e)/d the equivalent length to diameter ratio using the actual total pressure drop in the vertical inlet tangent leg. Generally l(e)/d values rose with gas rate, but exhibited an increasingly complex relation with f(o) the oil to liquid volumetric ratio as liquid rate was increased. A significant maximum in l(e)/d was in evidence around the inversion from water dominated to oil dominated flows. Several models are presented to predict the data. (C) 2007 Elsevier Inc. All rights reserved.