Influence of initial turbulence level on the flow and sound fields of a subsonic jet at a diameter-based Reynolds number of 10(5)

Five isothermal round jets at Mach number M = 0.9 and Reynolds number ReD=10(5) originating from a pipe nozzle are computed by large-eddy simulations to investigate the effects of initial turbulence on flow development and noise generation. In the pipe, the boundary layers are untripped in the first case and tripped numerically in the four others in order to obtain, at the exit, mean velocity profiles similar to a Blasius laminar profile of momentum thickness equal to 1.8 % of the jet radius, yielding Reynolds number ReD=900, and peak turbulence levels u'earound 0, 3 %, 6 %, 9 % or 12 % of the jet velocity uj.