Application of Computer Graphics Flow Visualization Methods in Vortex Rope Investigations

Abstract

Computer graphics visualization techniques for application on data from Computational Fluid Dynamics (CFD) simulations of the vortex rope, a phenomenon present in hydraulic turbines operating in off-design conditions, were devised. This included not only objects for visualization (what to visualize) but also methods of the visualization itself (how to do it). By means of advanced methods based particularly on volume rendering of Eulerian fields in combination with Lagrangian objects, various phenomena were captured, such as the motion of the vortex rope or the backflow zone. The data came from simulations using a scale-resolving hybrid turbulence model, the Stress-Blended Eddy Simulation. In such detailed simulations and other applications involving complex three-dimensional structures, proper visualization methods are needed to leverage the content captured in the resultant data.

Oscillation of Cavitating Vortices in Draft Tubes of a Simplified Model Turbine and a Model Pump–Turbine

“…The development of modern techniques and approaches for visualizing vortex flow, including computer graphics visualization using advanced methods based particularly on volume rendering of Eulerian fields, make a significant contribution to understanding the complex structure of the unsteady vortex flow [23]. However, vortex flow analysis can be carried out not only on the basis of velocity field data, but also using processing of high-speed imaging data.…”

On the existence of adverse pressure gradient in decelerated swirling flow and its suppression by water jet injection

“…For our research of the vortex rope phenomenon, we have designed a new swirl generator capable of changing the swirl intensity smoothly within a wide range while being constructionally simple, without any moving parts. Several studies of the flow in this swirl generator have already been published [12][13][14][15][16]. Its principle resides in mixing flows from two separate inlets -a straight axial inlet and a tangential inlet ended by a spiral case generating rotation.…”