The source of crackle noise in heated supersonic jets

High-fidelity large eddy simulation (LES) is used to investigate the source of crackle noise generated heated supersonic jets. Crackle is associated with intermittent N-shaped acoustics waves consisting of a sudden compression followed by a more gradual expansion, and is extremely irritating to human auditory perception. Results from four different simulations of jets produced by an experimental military-style nozzle reveal that N-shaped waves are generated directly by the jet turbulence, and thus nonlinear propagation effects are not a necessary component of their formation. Different operating points for the simulations were chosen such that jet velocity and jet temperature were varied independently. While crackle levels are sensitive to jet velocity, full field pressure skewness results suggest that increasing temperature may also play an independent role in enhancing crackle. The structure of the crackle source in the most strongly crackling jet is investigated by a backtracking algorithm applied to the simulation resulting in conditional averages.

[1]  Jonathan B. Freund,et al.  Near-Field Shocks Radiated by High-Speed Free-Shear-Flow Turbulence , 2014 .

[2]  Steve Martens,et al.  Practical Jet Noise Reduction for Tactical Aircraft , 2010 .

[3]  S. Lele,et al.  Interaction of a Taylor blast wave with isotropic turbulence , 2011 .

[4]  Ali Mani,et al.  Analysis and optimization of numerical sponge layers as a nonreflective boundary treatment , 2012, J. Comput. Phys..

[5]  F. Nicoud,et al.  Large-Eddy Simulation of the Shock/Turbulence Interaction , 1999 .

[6]  Charles E. Tinney,et al.  Nonlinear Noise Propagation from a Fully Expanded Mach 3 Jet , 2012 .

[7]  Lakshmi Venkatakrishnan,et al.  Crackle - A dominant component of supersonic jet mixing noise 13; 13; , 2000 .

[8]  Steve Martens,et al.  The Effect of Chevrons on Crackle: Engine and Scale Model Results , 2011 .

[9]  J. E. Ffowcs Williams,et al.  ‘Crackle’: an annoying component of jet noise , 1975, Journal of Fluid Mechanics.

[10]  Sanjiva K. Lele,et al.  High-fidelity large-eddy simulation for supersonic rectangular jet noise prediction , 2011 .

[11]  A. Lyrintzis,et al.  Analysis of Converging-Diverging Beveled Nozzle Jets Using Large Eddy Simulation with a Wall Model , 2015 .

[12]  Parviz Moin,et al.  Numerical simulation of a Mach 1.92 turbulent jet and its sound field , 2000 .

[13]  Sanjiva K. Lele,et al.  Crackle Noise in Heated Supersonic Jets , 2012 .

[14]  B. Greska,et al.  Mach Wave Radiation: a Review and an Extension , 2003 .

[15]  Sanjiva K. Lele,et al.  A modified artificial viscosity approach for compressible turbulence simulations , 2008, J. Comput. Phys..

[16]  Jonathan B. Freund,et al.  Source mechanisms of jet crackle , 2012 .

[17]  Christopher K. W. Tam,et al.  On the three families of instability waves of high-speed jets , 1989, Journal of Fluid Mechanics.

[18]  Kent L. Gee,et al.  On the Perception of Crackle in High-Amplitude Jet Noise , 2007 .

[19]  Sanjiva K. Lele,et al.  Nozzle wall modeling in unstructured large eddy simulations for hot supersonic jet predictions , 2013 .