The Numerical Simulation Of Air-water Two-phase Flow In Helical Pipelines

The helical pipelines are a kind of curve pipes widely used in engineering, chemical, petroleum and nuclear industries. The flow field is more complex because the influence of the centrifugal force and the gravity.The two-fluid model is developed for the adiabatic two-phase flow in the helical pipelines base on the Computational Fluid Dynamics. The two phases are governed by the separate continuity equation and the momentum equation. The interface forces including the drag force, virtual mass force, lift force and turbulence dispersion force are calculated in the momentum equations. The turbulent motion of the water phase is expressed with renormalization group (RNG) k-εtwo-equation model, and the low Reynolds number area nearby the wall is simulated with the wall function.The distortion and movement processes of the buoyant bubble in the vertical helical pipelines are simulated with the Level Set method. The field in the bubbles is also considered as parts of the solution subdomain to avoid the reiterative and complex correction of the interface shape during the solution. The interface of the air and water is processed by the local averaging method.The free mesh and geometric multigrid solver are used for the steady-state analysis of the flow field in horizontal helical pipelines. The simulation shows that the void fraction unevenness is the trigonometric function of the helical angle. And with the increase of the volume flow rate the void fraction trends to evenness because the influence of the turbulence dispersion force.