Inscrição na biblioteca: Guest
TSFP DL Home Arquivos Comitê executivo

EFFECTS OF NOZZLE-EXIT BOUNDARY-LAYER THICKNESS ON THE TURBULENT DEVELOPMENT OF INITIALLY LAMINAR CIRCULAR JETS

Christophe Bogey
Laboratoire de Mecanique des Fluides et d'Acoustique UMR CNRS 5509, Ecole Centrale de Lyon 69134 Ecully, France

Christophe Bailly
Laboratoire de Mecanique des Fluides et d'Acoustique UMR CNRS 5509, Ecole Centrale de Lyon 69134 Ecully, France

Resumo

Round jets at Mach number 0.9 and Reynolds number 105, displaying nozzle-exit boundary layers characterized by laminar Blasius velocity profiles, low velocity fluctuations and momentum thicknesses between 0.003r0 and 0.02r0, where r0 is the jet radius, are computed by Large-Eddy Simulation. The effects of the outlet boundary-layer thickness on initially laminar jets are investigated. Jets with thinner boundary layers show earlier but slower turbulent development, leading to longer potential cores and lower turbulence intensities. Their flow properties compare well with corresponding experimental data for jets at high Reynolds numbers. Finally the influence of adding random noise of low magnitude in the jet nozzle is also explored.