DOI: 10.1615/TSFP8
SWIRLING FLOW IN A TUBE WITH VARIABLY-SHAPED OUTLET ORIFICES: AN LES AND VLES STUDY
Краткое описание
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.