Direct Numerical Simulation of the Noise from a Mach 0.9 Jet

A Mach 0.9 jet at Reynolds number 3600 is simulated along with its radiated sound by direct numerical solution of the flow equations. The numerical simulation is shown to be in excellent agreement with experimental measurements at the same flow conditions. Basic turbulence and sound statistics are presented and analyzed. Pressure data is Fourier transformed in the streamwise direction and in time and this is used to compute the Lighthill acoustic source. Evaluation of Lighthill’s analogy shows good agreement with the directly computed sound field. Having validated both the simulation and Lighthill’s equation, a future direction is briefly outlined where a space/time Fourier analysis of the sources will be conducted. NOMENCLATURE a∞ Ambient speed of sound D Jet diameter k Streamwise wave number ρ Fluid density ρ j Jet exit fluid density ρ∞ Ambient fluid density r Radial coordinate measured from domain centerline ro Jet radius S Lighthill acoustic source StD Strouhal number = f D=U j τi j Viscous stress tensor U j Jet exit centerline velocity vx Axial velocity vr Radial velocity x Jet axial coordinate measured from nozzle