Experimental investigation and numerical study of multiphase flow characteristics in the M-shaped jumper with different bend curvature radii

The M-shaped jumper, a commonly used connecting pipeline in subsea production systems, typically consists of horizontal pipes, vertical pipes and several bends. Different bend curvature radii significantly influence the flow characteristics of fluids inside jumper. This paper investigates the multiphase flow characteristics in M-shaped jumpers with different bend curvature radii (radii of 1D, 1.5D, 2D, 3D, and 4D) at various flow velocities (1-2 m/ s) and water volume fractions (0.2-0.8) by experiments and simulations. Smaller bend curvature radii result in larger and more deformed Taylor bubbles due to increased shear forces and velocity gradients, leading to increased flow instability. In contrast, larger bend curvature radii generate smaller, more stable bubbles, resulting in smoother flow. Moreover, larger bend curvature radii enhance stratified flow by reducing gas-liquid mixing and stabilizing phase separation. Additionally, an increase in radius reduces overall pressure drop within the jumper, a radius of 1D exhibits a 10-12% higher pressure drop than a radius of 4D, as larger bend curvature radii minimize gas-liquid mixing at bends. The water volume fraction also affects the pressure drop, peaking at 50% due to intensified phase interactions. Larger bend curvature radii in M-shaped jumpers improve flow stability and efficiency while decreasing pressure losses.