Experimental data on a three dimensional flow field around an obstacle in a vertical pipe

In many industrial applications, i.e. constrictions, expansions and various valves, three dimensional two-phase flows occur. Two-phase flows over an asymmetric obstacle create pronounced 3D structures, including: flow separation at the obstacle edge, recirculation zone and vortex formation in the wake of them as well as strong shear fields with curved streamlines and large angles.
The presentation starts with a description of the test section, the measuring technique and the boundary conditions of the required experiments. Furthermore, algorithms and equations for estimation of the axial liquid and the lateral bubble velocities were given. The results of the data treatment are shown in cross section views of the tube in well defined distances under and above the obstacle. Additionally, comparisons of void fractions and liquid velocities of selected experiments were discussed. In this context it is possible to identify from the plots the stagnant point upstream the obstacle and the flow separation zone as well as recirculation and reattachment phenomena.
The ability to build 3D sets of data makes it useable to validate CFD codes and proof new implemented models. The work will be continued.