NUMERICAL PREDICTION OF LAMINAR, TRANSITIONAL AND TURBULENT FLOWS IN SHROUDED ROTOR-STATOR SYSTEMS

The paper deals with numerical prediction of laminar, transitional and turbulent regimes in confined flow between rotating and stationary di scs. For the laminar and transitional flows, a spectral tau-Chebyshev method associated with a multistep time scheme is used. This approach allows accurate prediction of the two laminar regimes mentioned by Dai ly and Nece (1960) in their experimental studies. For the geometry und er consideration (1/11 aspect ratio), the transition to unsteady motio n occurs abruptly without any oscillatory behavior. Thus, the instabil ities develop in a region localized near the external shroud, primaril y along the stator side, according with experimental findings. For cal culating turbulent flow regimes, one point second-order transport mode ling has been implemented in a finite volume code. The superiority of advanced Reynolds stress transport models over the classical k - epsil on model is decisive for predicting such a complex flow. This is parti cularly important in order to get a precise delineation of the adjacen t turbulent and relaminarized regions within the cavity. This level of closure was crucial to produce numerical results in good agreement wi th experimental data. (C) 1997 American Institute of Physics.