Summary

In this dissertation methods based on the numerical solution of theReynolds-averaged Navier?Stokes equations are evaluated to predictjet noise. The flow conditions include Reynolds number around 106and Mach number in the 0.50?1.00 range, isothermal or heated fluidstreams, single- and dual-stream circular nozzles with or without chevrons.The prediction of jet noise can be split in two components: theevaluation of the strength of sound sources and the evaluation of thee?ects of sound refraction. Four methods available in the literature areimplemented to evaluate the source strength; two based on the LighthillEquation and two based on the Linearized Euler Equations. It is foundthat both frameworks allow predictions of noise spectra in reasonableagreement with experimental data. However, the methods based onthe Lighthill Equation o?er a more straightforward formulation andneed less empirical constants. A ray tracing method is also adopted tostudy the e?ects of refraction on acoustic pressure waves emitted frommonopole sources in several positions within the jet. Three aspectsof refraction are studied in detail: (i) the dependence of the zone ofsilence regarding the source position, (ii) the significance of sound speedgradients in heated jets, and (iii) the asymmetry created by chevronnozzles. Given the reasonable accuracy and low computational cost ofthe studied methods, the so-called RANS-based methods are considereda viable approach to predict jet noise.

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