Simulation of vortex breakdown in an enclosed cylinder as a preliminary study of the draft tube vortex rope creation

摘要

Vortex breakdown occurs as instability of the steady flow in many engineering applications (turbine diffusers, swirl chambers, etc.). Paper presents investigation of this phenomena in an enclosed cylinder. This original problem is further extended to study the influence of the cone inserted inside the cylinder. The cone shape (sharp or blunted) and the cone rotation are examined. It is concluded that especially cone rotation significantly influences the initiation of vortex breakdown and the overall flow pattern.