Transitional-turbulent flow with heat transfer in a closed rotor-stator cavity
Résumé
In this paper, a non-isothermal flow confined between a rotating and a stationary disc is investigated using direct numerical simulation. Besides its fundamental importance as a three-dimensional prototype flow, such flows arise in many industrial devices, especially in turbomachinery applications. Our aim is to include the effects of density variation as this introduces a quasi-buoyant effect on the near-wall layers due to the radial acceleration, Ω2 r. None of the detailed experimental studies of disc-cavity flows has examined this effect due to the extreme flow conditions arising in an actual gas turbine. As a preliminary exploration we show here the effects on the mean flow of Rayleigh numbers up to 2 × 106. The direct numerical simulation is performed by integrating the time-dependent Navier-Stokes equations with a three-dimensional spectral method. The Boussinesq approximation is used to take into account the centrifugal-buoyancy effects. The effects of thermal convection have been examined for a transitional-turbulent flow at Re (=ΩR 1 2/ν) = 110 000 in an annular cavity of aspect ratio L (=ΔR/H) = 2.35. These DNS results provide accurate, instantaneous quantities which are of interest in understanding the physics of turbulent flow and heat transfer in a rotating disc cavity. Moreover, the averaged results show small effects of density variation and provide target data for researchers employing RANS schemes.