Modelling of jet noise: a perspective from large-eddy simulations

Abstract

In the last decade, many research groups have reported predictions of jet noise using high-fidelity large-eddy simulations (LES) of the turbulent jet flow and these methods are beginning to be used more broadly. A brief overview of the publications since the review by Bodony & Lele (2008, AIAA J. 56 , 346–380) is undertaken to assess the progress and overall contributions of LES towards a better understanding of jet noise. In particular, we stress the meshing, numerical and modelling advances which enable detailed geometric representation of nozzle shape variations intended to impact the noise radiation, and sufficiently accurate capturing of the turbulent boundary layer at the nozzle exit. Examples of how LES is currently being used to complement experiments for challenging conditions (such as highly heated pressure-mismatched jets with afterburners) and guide jet modelling efforts are highlighted. Some of the physical insights gained from these numerical studies are discussed, in particular on crackle, screech and shock-associated noise, impingement tones, acoustic analogy models, wavepackets dynamics and resonant acoustic waves within the jet core. We close with some perspectives on the remaining challenges and upcoming opportunities for future applications. This article is part of the theme issue ‘Frontiers of aeroacoustics research: theory, computation and experiment’.

Amplitude Scaling of Wave Packets in Turbulent Jets

“…The coordinate system used throughout this work is the same used in [18] and shown in figure 1, where , , , and are the axial, radial, azimuthal, and polar coordinates, respectively, and the origin is at the center of the nozzle exit. All LES results are in close agreement with accompanying experiments, conducted at the Pprime Institute [18,20,22]. The measured turbulent flow spectra are broadbanded, and the LES results are in close agreement with experimental spectra up to a Strouhal number of 2.7.…”

“…This work relied on the numerical simulations described in Brès et al [18,20]. These are large eddy simulations (LES) of an isothermal subsonic jets, which exhaust from a converging-straight round nozzle, shown in figure 1.…”

“…Simulations were performed for Mach numbers = 0 = 0.4 and 0.9, based on jet exit velocity and ambient sound speed 0 . A range of Mach numbers 0.4, 0.7, 0.8 and 0.9 were simulated and validated against experimental measurements [18,20]. Here, the focus is on the Mach 0.4 and 0.9 cases as representative of low and high-subsonic jets.…”

Acoustic tones in the near-nozzle region of jets: characteristics and variations between Mach numbers 0.5 and 2

“…Considerable advancements have been made in the last few years in the field of jet aeroacoustics, as highlighted in the reviews of Brès & Lele (2019) and Lyrintzis & Coderoni (2020) on jet noise prediction and modelling using large-eddy simulations, and that of Edgington-Mitchell (2019) on aeroacoustic resonance and self-excitation in supersonic jets, for instance. They have provided new insights into jet flow and noise generation mechanisms.…”

Compressibility Modified RANS Simulations for Noise Prediction of Jet Exhausts with Chevron

“…In recent years, with the significant development of the computational capability, high-fidelity turbulence methods are becoming applicable for jet noise predictions, such as LES (Large Eddy Simulation), hybrid RANS/LES methods. It has been reviewed in recent literature (Bres and Lele 2019). Xia et al (2009) applied LES to study the jet noise with 0.9 Mach number using around 12.5 million computational grids.…”