Prediction of Shock-Cell Structure and Noise in Dual Flow Nozzles

Abdelhamid, Yahia; Ganz, Ulrich

doi:10.2514/6.2007-3721

Cited by 6 publications

(4 citation statements)

References 5 publications

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“…When comparing against the experimental results, the turbulence model k − ω gives the best results in terms of shock amplitude, but it overestimates the length of the potential core by more than 50%. Similar decays are found in the literature when using different turbulence models [28,80,1]. According to these results, the Spalart-Allmaras model has a similar performance than the other turbulence models with the advantage of having only one equation, and thus being numerically more efficient and less computationally expensive to simulate several cases for uncertainty quantification purposes.…”

Section: Turbulence Modelsupporting

confidence: 85%

On the influence of uncertainty in computational simulations of a high-speed jet flow from an aircraft exhaust

et al. 2019

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A classic approach to computational fluid dynamics is to perform simulations with a fixed set of variables in order to account for parameters and boundary conditions. However, experiments and real-life performance are subject to variability in their conditions. In recent years, the interest of performing simulations under uncertainty is increasing, but this is not yet a common rule, and simulations with lack of information are still taking place. This procedure could be missing details such as whether sources of uncertainty affect dramatic parts in the simulation of the flow. One of the reasons of avoiding to quantify uncertainties is that they usually require to run an unaffordable number of CFD simulations to develop the study. To face this problem, Non-Intrusive Uncertainty Quantification (UQ) has been applied to 3D Reynolds-Averaged Navier-Stokes simulations of an under-expanded jet from an aircraft exhaust with the Spalart-Allmaras turbulent model, in order to assess the impact of inaccuracies and quality in the simulation. To save a large number of computations, sparse grids are used to compute the integrals and built surrogates for UQ. Results show that some regions of the jet plume can be more sensitive than others to variance in both physical and turbulence model parameters. The Spalart-Allmaras turbulent model is demonstrated to have an accurate performance with respect to other turbulent models in RANS, LES and experimental data, and the contribution of a large variance in its parameter is analysed. This investigation explicitly outlines, exhibits and proves the details of the relationship between diverse sources of input uncertainty, the sensitivity of different quantities of interest to said uncertainties and the spatial distribution arising due to their propagation in the simulation of the high-speed jet flow. This analysis represents first numerical study that provides evidence for this heuristic observation.

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Section: Turbulence Modelsupporting

confidence: 85%

On the influence of uncertainty in computational simulations of a high-speed jet flow from an aircraft exhaust

et al. 2019

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“…However it is not in the region where the oscillations are largest that the BBSAN sources are concentrated; these sources seem further downstream. As shown by Michel [32] and observed by Abdelhamid and Ganz [28], strong shocks do not seem required to generate BBSAN. In moderately under-expanded conditions, the broadband shock noise is the product of an interaction between the turbulence and the almostperiodic mean flow-field created by the successive expansions and compressions of the propulsive jet.…”

Section: Flow-fieldmentioning

confidence: 76%

“…Airbus ran extensive CFD studies to interpret the various test results. As reported by Abdelhamid and Ganz [28], accurate Reynolds-Averaged Navier-Stokes (RANS) based flow predictions of shock-cell structure may be used to gain more physical insight of shock-cell structure and improve shock-cell noise interpretations in dual under-expanded nozzle flows. Airbus performed RANS CFD with k-ω turbulence model on meshes refined up to 15 fan nozzle diameters after the fan nozzle exhaust section plane to better capture mixing and shock cells.…”

Section: Cfd Analysismentioning

confidence: 99%

Understanding and Reduction of Cruise Jet Noise at Aircraft Level

Huber

Bulté

Laurendeau³

et al. 2014

International Journal of Aeroacoustics

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Within the LINFaN research project, Airbus and Rolls-Royce have jointly investigated the acoustic impact of supersonic jet noise on the fuselage of an Airbus A340 equipped with Rolls-Royce Trent 500 engines in cruise conditions. The main results are presented in this paper. The influence of chevron fan nozzles designed to reduce cruise jet noise on the rear fuselage is investigated. The characterization of both the acoustic field and the aerodynamic flow is carried out. The acoustic data are obtained from a microphone array on the rear fuselage. After specific data de-noising, the acoustic spectra radiated on the fuselage by only the right inner engine are estimated. Beamforming acoustic maps are also computed to localize the jet noise sources. Besides, the supersonic jet flows are characterized by RANS CFD approach. For the baseline round nozzle, the acoustic results show the presence of two distinct broadband shock-associated noise contributions on the fuselage. The first pattern is observed in the far aft section of the fuselage for Strouhal numbers based on the jet mixing diameter and velocity between St = 4 and 6. The other pattern, around St = 1, radiates preferably forward. In addition, the high frequency source is located between 4 and 5 mixed jet diameters past the secondary nozzle exhaust plane, while the low frequency source is located farther downstream between 7 and 8 mixed jet diameters. Shock-associated noise is usually associated with the interaction between shock cells and turbulent shear-layers. We postulate that the high-frequency noise component results from the interaction between the shock-cells in the secondary flow and the inner shear-layer, while the low-frequency component is due to the interaction between shock cells and the outer shear-layer. This interpretation is consistent with two observations. The first observation is a strong modification of the measured high frequency noise when the engine is pushed to high power. At

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“…Therefore, two possible shock-associated noise sources from the interaction with both shear layers appear. Abdelhamid et al 22 found that the high frequency components developed in the primary shear layer whereas the low frequency components originated on the secondary shear layer. This phenomena was further studied by Tam et al who developed a model 23 able to predict the shock-associated noise frequency peaks from both primary and secondary shear layer using a Fourier decomposition of the shock-cell system.…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulation of Shock-Cell Noise From a Dual Stream Jet

Arroyo

Puigt

Airiau

et al. 2016

22nd AIAA/CEAS Aeroacoustics Conference

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This study presents the shock-cell noise results obtained with a large eddy aeroacoustic simulation from a dual stream jet. The primary stream is cold and subsonic with an exit Mach number of Mp = 0.89 and a Reynolds number of Rep = 0.57 × 10 6. The secondary stream is cold supersonic and under-expanded with a perfectly expanded Mach number of Ms = 1.20 and Res = 1.66 × 10 6. The computations are performed with the structured multiblock solver elsA. The aerodynamics and aeroacoustics of the flow are studied and analyzed in detail showing good agreement with experimental fits for the lengthscale and shear layer development. An acoustic-hydrodynamic filtering is used in order to compute the characteristic wavelengths of each component and estimate the shock-cell noise frequency. Moreover, the broadband shock-cell noise is captured in the near and far fields.

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Prediction of Shock-Cell Structure and Noise in Dual Flow Nozzles

Cited by 6 publications

References 5 publications

On the influence of uncertainty in computational simulations of a high-speed jet flow from an aircraft exhaust

On the influence of uncertainty in computational simulations of a high-speed jet flow from an aircraft exhaust

Understanding and Reduction of Cruise Jet Noise at Aircraft Level

Large Eddy Simulation of Shock-Cell Noise From a Dual Stream Jet

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