Flow and acoustic characteristics of non-axisymmetric jets at subsonic conditions

Upadhyay, Puja; Valentich, Griffin; Kumar, Rajan; Alvi, Farrukh S.

doi:10.1007/s00348-017-2340-z

Cited by 10 publications

(4 citation statements)

References 39 publications

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“…It had been also observed by Ahuja et al [34] that rectangular nozzles with aspect ratio AR = 3.6 can be slightly noisier than circular ones in subsonic conditions, especially for the radiation angles perpendicular to the long edge of the nozzle. Similar conclusions were obtained by Upadhyay et al [12] for a rectangular nozzle outlet with AR = 4, operated at M a = 0.9. Despite its small aspect ratio of 1.22:1, the rect-22 nozzle features some corners that induce streamwise About the noise reduction, it should be first reminded that the long edge of the rectangular nozzle is parallel to the plate so that increasing the AR is also augmenting the distance between the shear layer and the plate, potentially beyond the k r = 2 limit for some high frequencies.…”

Section: Circular Vs Rectangular Nozzlessupporting

confidence: 89%

“…Noise reduction techniques have been thoroughly investigated in literature for isolated jets [10] using for example tabs or chevrons [11], asymmetrical [12,13] or beveled nozzles [14,15]. These techniques have shown promising noise reduction potential for isolated jets, some of them have found their way to production engines and have effectively reduced aircraft noise during take-off, when the jet constitutes a significant contribution to the noise footprint.…”

Section: Introductionmentioning

confidence: 99%

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Jet noise and wing installation effects of circular, beveled and rectangular nozzles

Christophe

Decker

Schram

2023

Preprint

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With the growth of modern turbofan engines, their integration under the wing becomes challenging and induces aerodynamic and acoustic interactions between the jet exhaust and the airframe. Jet noise reduction techniques have been widely studied over the past decades but their efficiency has still to be demonstrated once installed. The present lab-scale jet experiments at Mach 0.6 compare the noise radiated by beveled and rectangular installed nozzles to circular ones on a quarter-sphere radiation map using a microphone antenna. For all radiation angles, modified nozzles show an amplitude decrease of the jet-plate interaction tones of the noise spectra attributed to a strong coupling between the jet shear layers and the sound scattering at the plate trailing edge. Circular nozzles achieve a noise reduction for all radiation angles with a maximum decrease up to 2~dB at receiver locations perpendicular to the plate. While rectangular nozzles show a similar behavior, a sound increase is observed for listeners parallel to the plate when the height-to-width ratio is small.

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Section: Circular Vs Rectangular Nozzlessupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Jet noise and wing installation effects of circular, beveled and rectangular nozzles

Christophe

Decker

Schram

2023

Preprint

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“…The Mach disc formed in the case of an elliptic jet is small compared to the circular jet. Upadhyay et al 29 demonstrated the influence of nozzle geometry on the evolution of an air jet using a stereoscopic PIV. The enhanced mixing for asymmetric jets is revealed by the shorter core length, faster decay of velocity, and higher shear layer growth rate.…”

Section: Introductionmentioning

confidence: 99%

Effects of circular and non-circular nozzle exit geometries on subsonic and supersonic jet propagations

Thangaraj

Kaushik

Thanigaiarasu

2022

Proceedings of the Institution of Mechanical Engineers, Part G:

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The mixing enhancement and core length reduction of a jet without significant loss of thrust are essential for reducing infrared radiation, mitigating aeroacoustic noise, improving combustion characteristics, and thrust vectoring. The jet mixing can be improved by manipulating the flow behavior. In subsonic and sonic jets, the flow manipulation may be achieved by utilizing nozzles with non-circular geometries that shed vortices of varying size due to their non-uniform azimuth curvatures. Non-uniform vortices generate differential spreading along the nozzle’s perimeter, causing axis switching and improving entrainment characteristics. Therefore, the present study examines the effects of two non-circular nozzle exit shapes (elliptic and square) on the mixing augmenting efficacy at subsonic and sonic flow conditions. The circular nozzle is tested for comparison. Both quantitative and qualitative analyses evaluate the efficacy of nozzles with non-circular exit geometries. Among the configurations investigated, the elliptic nozzle is superior in shortening the potential core length and enhancing the jet spread. A maximum reduction of 18.75% in core length with rapid jet decay was accomplished with the elliptic nozzle. The measurement of pressure profiles at different streamwise locations reveals that the spread rate is greater for elliptic and square jets than their circular counterpart. The elliptic jet exhibits the highest spread along the minor-axis direction compared to the major-axis direction. The differential jet spread rate in the elliptical jet causes an early axis-switching––direct evidence of mixing augmentation. Shadowgraph images show the asymmetric pattern of shock cell structures and differential spreading in elliptic and square jets.

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“…Cao et al [17] used a new computational method to model the flow of nanofluids in a cavity with a corrugated inner wall with uniform flux. Upadhyay et al [18] studied the flow and acoustic characteristics of rectangular and elliptical asymmetric jets and compared them with the equivalent area of circular jets. Xiao et al [19] established a single-nozzle model with different transverse velocities and studied the characteristics of jet flow fields and deflection.…”

Section: Introductionmentioning

confidence: 99%

Vortex of a Symmetric Jet Structure in a Natural Gas Pipeline via Proper Orthogonal Decomposition

Li,

Lu,

Zhao

et al. 2024

Processes

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The impact of particle addition jets on the flow field in natural gas pipelines was investigated, and the structural information of the flow field at different flow velocities in a symmetric jet flow was analyzed via numerical simulation. The results of coherent structures in the high-pressure natural gas pipeline reveal vortex structures of varying sizes both upstream and downstream of the jet flow. To determine the spatial distribution of the main vortex structures in the flow field, proper orthogonal decomposition (POD) mode analysis was performed on the unsteady numerical results. Moreover, the detailed spatial characteristics of the coherent vortex structures represented by each mode were obtained. The results indicate that the large-scale vortex structures within the pipeline are balanced and stable, with their energy increasing as the jet flow velocity increases. Additionally, higher-order modes exhibit significant shedding of small-scale vortex structures downstream of the jet flow. In this research, coherent structures present in symmetric particle addition jets are provided, offering theoretical support for future investigations on the distribution of particle image velocimetry (PIV) flowmeters.

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Flow and acoustic characteristics of non-axisymmetric jets at subsonic conditions

Cited by 10 publications

References 39 publications

Jet noise and wing installation effects of circular, beveled and rectangular nozzles

Jet noise and wing installation effects of circular, beveled and rectangular nozzles

Effects of circular and non-circular nozzle exit geometries on subsonic and supersonic jet propagations

Vortex of a Symmetric Jet Structure in a Natural Gas Pipeline via Proper Orthogonal Decomposition

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