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SWIRLING FLOW IN A TUBE WITH VARIABLY-SHAPED OUTLET ORIFICES: AN LES AND VLES STUDY

C.-Y. Chang
Institute of Fluid Mechanics and Aerodynamics / Center of Smart Interfaces Technische Universitat Darmstadt Petersenstr. 30 / 32, D-64287 Darmstadt, Germany

K. Dietrich
Institute of Fluid Mechanics and Aerodynamics (SLA) / Center of Smart Interfaces (CSI) Technische Universitat Darmstadt Petersenstr. 17 D-64287 Darmstadt, Germany

Suad Jakirlic
Department of Mechanical Engineering Institute of Fluid Mechanics and Aerodynamics (SLA) / Center of Smart Interfaces (CSI) Technische Universitat Darmstadt Petersenstrasse 17, D-64287 Darmstadt, Germany

F. Wassermann
Institute of Fluid Mechanics and Aerodynamics (SLA) / Center of Smart Interfaces (CSI) Technische Universitat Darmstadt Petersenstr. 17 D-64287 Darmstadt, Germany

Sven Grundmann
Department of Mechanical Engineering Institute of Fluid Mechanics and Aerodynamics (SLA) / Center of Smart Interfaces (CSI) Technische Universitat Darmstadt Petersenstrasse 17, D-64287 Darmstadt, Germany

Cameron Tropea
Technische Universität Darmstadt, Institute of Fluid Mechanics and Aerodynamics, Center of Smart Interfaces, International Research Training Group Darmstadt-Tokyo on Mathematical Fluid Dynamics, Germany

Branislav Basara
AVL LIST GmbH, Advanced Simulation Technologies, Hans List Platz 1, 8020 Graz, Austria

Abstrakt

The swirling flow in a tube with the outlet designed in the form of an orifice nozzle with centered and eccentrical openings, investigated experimentally by Grundmann et al. (2012), was studied computationally by employing Large Eddy Simulation (LES) method and a Hybrid LES/RANS (Reynolds-Averaged Navier-Stokes) method. The latter method, denoted by VLES (Very Large Eddy Simulation) according to Speziale (1998), represents a variable resolution computational scheme enabling a seamless transition from RANS to the direct numerical solution of the Navier-Stokes equations (DNS) depending on the ratio of the representative grid spacing to the length scale of energy containing eddies which varies within the flow domain. The background RANS model representing the basis of the VLES method is the k − ε − ζ − ƒ model proposed by Hanjalic et al. (2004). The inflowing swirl generated by two tangential inlets has the same intensity in all cases considered. However, the abrupt outlet cross-section contraction created by variably-shaped orifices causes strong modification of the flow within the tube resembling a three-layered structure with alternating axial velocity directions. Both LES and VLES methods, unlike the RANS method employing the same turbulence model, returned such a behavior in good agreement with experimental data.