CFD analysis on experiments of bubbly flow in a tube with an obstacle


CFD analysis on experiments of bubbly flow in a tube with an obstacle

Krepper, E.; Neumann, M.; Lucas, D.

Two phase adiabatic air/water flow in a vertical tube with an inner diameter of 54 mm equipped with an inner obstacle was investigated. Experiments are conducted for a wide range of superficial gas and liquid velocities in bubbly flow regime. Flow obstacles, namely a ring shaped diaphragm and a half-moon shaped diaphragm, are used for generation of three-dimensional flow fields. Besides conventional measurement techniques an ultrafast X-ray tomography scanner ROFEX, which was developed by HZDR, are applied. ROFEX determines gas distributions, bubble velocities and bubble sizes (Hampel et al. 2013, 2016).
The experiments were used to analyze the capability of the actual CFD based on the Euler/Eulerian approach. The CFD calculations were performed as pre-test simulations. Measured results for half-moon shaped diaphragm tests were available short before publishing the manuscript and shown with the calculations. Most of the values and at least the tendencies could be predicted with good agreement to measurements. Reasons for deviations are discussed in the paper.
CFD simulation enables the investigation of single components of the model approach. So the distribution of the bubble forces and the strength and location of single breakup&coalescence mechanisms can be analyzed and checked for plausibility.

Keywords: bubbly flow; experiments; CFD; momentum exchange; bubble induced turbulence; bubble breakup & coalescence

  • Contribution to proceedings
    The 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17), 03.-08.09.2017, Xi'an, China
  • Lecture (Conference)
    The 17th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-17), 03.-08.09.2017, Xi'an, China

Permalink: https://www.hzdr.de/publications/Publ-26088
Publ.-Id: 26088