Hydrodynamic forces in a horizontal-horizontal elbow in a gas-liquid system

Understanding the force fluctuations in an elbow is critical for piping system design, especially in multiphase flow applications. A new experimental facility has been designed and built where flow parameters, structural forces, and pressure upstream and downstream of the elbow can be measured simultaneously. The new facility allowed the study of the impact of different flow patterns on the phenomenon, with a wide range of liquid and gas superficial velocities (vSL 0.1-2.5 m/s, vSG 1-10 m/s). Oil and air have been used to represent field conditions better. In-situ liquid holdup and structure or translational velocity instead of mixture velocity are characterized. The flow influence as the peak force magnitude was measured on a single elbow (90-degree) oriented in a horizontal-horizontal configuration to identify the flow parameters with the most effect on the force. The results show that the density and velocity of coherent flow structures are essential to describe the force fluctuation. Additionally, pressure fluctuations in the elbow are significant for estimating the force in specific flow patterns.