Axisymmetric numerical simulations of turbulent flow in rotor stator enclosures
Résumé
We present axisymmetric numerical simulations of transitional andchaotic flow regimes in rotorstator cavities of radial aspect
ratio approximately 8. These simulations are carriedout using a secondord er time andspace accurate algorithm which integrates
the axisymmetric unsteady NavierStokes equations in stream function-azimuthal vorticity-azimuthal velocity form. Detailed flow analysis has been carried out for selectedvalues of the rotational Reynolds number (Reh) up to 106. At the largest value considered,
computations have been performed using 4096 mesh points in the radial direction, which has required using a multi-domain decomposition algorithm implementedon a parallel machine. The limitations and consequences of the axisymmetry assumption are
first discussedandchecked against available experimental results. The evolutions of the instantaneous flow structure andof its first
and second order statistic moments as the Reynolds number increases are discussed. It is shown that the dynamics of the flow mainly
consists of travelling waves propagating in the stator androtor boundary layers andof inertial waves in the core region, and that for
moderate Reynolds numbers (Reh 3 x 10(5)), the rotor boundary layer is almost completely steady while large amplitude fluctuations
are found in the stator boundary layer. The evolution of second order moments confirms the fundamentally asymmetrical role of the boundary layers along the rotor and along the stator. A turbulent kinetic energy budget is shown which exhibits some specific
features attributedto the rotation effects andto a lesser extent to the axisymmetry assumption.