Aero-acoustic Characteristics of Compressible Jets from Chevron Nozzle

Nikam, Shailesh R.; Sharma, S.K.

doi:10.2514/6.2014-2623

Cited by 6 publications

(5 citation statements)

References 9 publications

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“…The nozzle geometry considered in the present study is the same as the one used in the experimental study of Nikam and Sharma [29]. The nozzle exit diameter D is 30 mm and the exit Mach number is 0.8.…”

Section: Problem Description and Computational Methodologymentioning

confidence: 99%

“…Seven receivers were kept at a radial distance of 45D with a polar angle(θ) starting from 30° to 90° (in increments of 10°). These were the locations specified by Nikam and Sharma [29] as shown in Figure 2. OASPL was obtained by using FFT (Fast Fourier Transform) of the sound signal.…”

Section: Oaspl-acoustic Propertiesmentioning

confidence: 97%

“…Potential core length is the non-dimensionalized length at which the U/U j reduces to 0.95 from 1.00 (Mendez et al [34]). The potential core length is compared with the experimental data of Sharma and Nikam [29] in Figure 6. It can be clearly seen that the LES-WALE, LES-Smagorinsky, and DDES models have over-predicted the potential core length, whereas the URANS prediction is reasonably good.…”

Section: Potential Core Lengthmentioning

confidence: 99%

“…The increase in noise level at lower polar angles (say at 30 • ) in comparison to that at a polar angle of 90 • can be noted in the experimental data. Sharma and Nikam [29] attribute this to the directivity of the source. Both LES and DDES are able to capture this trend in the simulation.…”

Section: Oaspl-acoustic Propertiesmentioning

confidence: 99%

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Acoustic Modeling of Compressible Jet from Chevron Nozzle: A Comparison of URANS, LES and DES Models

et al. 2022

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Chevron nozzles, which are characterized by the serrations at the nozzle exit, are widely used for suppressing jet noise in aircraft engines. The noise suppression is accomplished by the enhanced mixing of the exhaust streams, which, in turn, is a result of the streamwise vorticity induced by the serrations. The present study focuses on the numerical modeling of the acoustic field in a compressible jet issuing from a chevron nozzle at a Mach number of 0.8. The study evaluates the effectiveness of turbulence modeling approaches of Large Eddy Simulation and Detached Eddy Simulation methods and compares them with the less computationally intensive Unsteady Reynolds Averaged Navier–Stokes (URANS) formulation. The Ffowcs Williams–Hawkings noise model was used to predict the overall sound pressure level in the far field. The LES predictions of the acoustic signature were found to match well with the experimental data, whereas the URANS model grossly underpredicted the sound pressure levels in the compressible jet flow field.

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Section: Problem Description and Computational Methodologymentioning

confidence: 99%

Section: Oaspl-acoustic Propertiesmentioning

confidence: 97%

Section: Potential Core Lengthmentioning

confidence: 99%

Section: Oaspl-acoustic Propertiesmentioning

confidence: 99%

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Acoustic Modeling of Compressible Jet from Chevron Nozzle: A Comparison of URANS, LES and DES Models

et al. 2022

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“…Chevrons are known to induce streamwise vorticity in the shear layer, which leads to enhanced mixing and reduced potential core length [33,43]. This is accompanied by the shifting of the acoustic energy of the flow noise sources [44], from low (commonly associated with large-scale structures in the flow) to high (usually attributed to small-scale turbulent structures) frequencies [33]. To emphasize the differences of both the nozzles, baseline (Figs.…”

Section: Initial Researches On Isolated Jets and Undergoing Investigamentioning

confidence: 99%

Development, validation and application of a newly developed rig facility for investigation of jet aeroacoustics

Bastos

Deschamps

Silva

et al. 2018

J Braz. Soc. Mech. Sci. Eng.

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Over the last decades, significant improvements have been achieved in terms of noise reduction for jet engine aircraft. Nevertheless, jet noise remains one of the major sound sources from commercial aircraft, particularly during takeoff. To develop strategies for jet noise reduction, it becomes paramount to understand the mechanisms of sound production and radiation from the experimental point of view. For this reason, researchers need high-quality noise data, obtained under proper conditions for both the acoustic and flow fields of scaled jets. This paper reports the development, validation and application of a new jet rig facility built at Federal University of Santa Catarina for investigations of jet noise. Issues relating to limited budget, deadline fulfillment and inner space restrictions, made the design and construction of the facility particularly difficult. Such drawbacks were overcome by designing carefully every system making up the whole facility, some of them based on CFD analyses, as well as by employing tailored solutions to some systems. Throughout the paper, the infrastructure of facility and its main systems are presented as well as major design requirements are discussed. Subsequently, the free-field qualification and the determination of acoustic far-field for the jet source, concerning the anechoic chamber, are described. With the aim of evaluating the acoustic performance of the facility, noise data were acquired for jet flows with Mach numbers from 0.3 to 0.9 and observer locations from 60 to 150 degrees. Additionally, hotwire anemometry measurements were performed at different axial positions along the jet to illustrate the turbulent character of flows generated. Results of flow and noise measurements revealed an acoustically clean signature as well as turbulence properties in good agreement with data from other facilities. Finally, the paper outlines the underway research works at the mentioned facility and new directions for further work.

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Experimental investigation of the far-field noise due to jet-surface interaction combined with a chevron nozzle

2017

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Aero-acoustic Characteristics of Compressible Jets from Chevron Nozzle

Cited by 6 publications

References 9 publications

Acoustic Modeling of Compressible Jet from Chevron Nozzle: A Comparison of URANS, LES and DES Models

Acoustic Modeling of Compressible Jet from Chevron Nozzle: A Comparison of URANS, LES and DES Models

Development, validation and application of a newly developed rig facility for investigation of jet aeroacoustics

Experimental investigation of the far-field noise due to jet-surface interaction combined with a chevron nozzle

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