Decomposition of the Navier-Stokes equations for noise source quantification within turbulent jets

• Published in: The Journal of the Acoustical Society of America 2019-10, Vol.146 (4), p.3001-3001
• Main Authors: Miller, Steven A., Patel, Trushant K., Shen, Weiqi
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.5137393

Jet noise remains a community annoyance and a major source of hearing damage for military personnel. The physical and mathematical understanding of the noise source are critical for the purpose of its reduction. We decompose the flow-field into a base flow, large-scale spatially coherent structures, small-scale relatively incoherent structures, and associated radiated noise components. The large-scale and fine-scale structures are ascertained via an additional numerical decomposition approach. An acoustic analogy based model is used to predict the noise from the relatively small-scale incoherent turbulence and the large-scale coherent turbulence interacting with the shock-cell structure. We examine these source models combined with the decomposition of large-eddy simulation (LES). We show validated noise predictions of our LES solver with both the Ffowcs Williams and Hawkings equation and our newly developed jet noise model. We evaluate the source models obtained from the acoustic analogy, that are the two-point cross-correlations of the Navier-Stokes equations, to quantify all noise sources. The major advantage of the developed approach is the ease of quantifying both the shock-associated noise and the fine-scale mixing noise sources. Finally, we discuss how our model can be used with existing LES of turbulent flows for noise reduction.