Broadband Shock-Associated Noise in Screeching and Non-Screeching Underexpanded Supersonic Jets

Bleich, André; Castelain, Thomas; Bailly, Christophe

doi:10.2514/1.j052058

Cited by 85 publications

(59 citation statements)

References 36 publications

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“…Though the screech amplitude was drastically modified by the application of any of the investigated chevron configurations, the measured screech frequencies were relatively unchanged. Similar results have been presented in the past [8,43,44]. It is possible that the standing wave spacing (not measured here) was unchanged, resulting in unchanged screech frequency following the results of Panda [45].…”

Section: Acoustic Fieldsupporting

confidence: 87%

“…First, the mean shock spacing was determined by averaging the shock spacing determined by consecutively subtracting the axial locations of the profile's peak velocity. Only the first six shock cells were used to eliminate the effect of screech on the calculated parameter, following the results of André et al [43]. Fig.…”

Section: Flow Fieldmentioning

confidence: 99%

“…Following the reasoning of Tam [50], which indicated that the upstream Mach disk was uncorrelated with shock noise levels, the most upstream shock strength was excluded from the average calculation. Additionally, the number of shock cells used for the strength calculation was limited to six following the results of André et al [43] as discussed above. A slightly modified shock strength characterization parameter of Tam [50] was developed for comparison purposes.…”

Section: Flow Fieldmentioning

confidence: 99%

See 2 more Smart Citations

Impact of chevron spacing and asymmetric distribution on supersonic jet acoustics and flow

Heeb

Gutmark

Kailasanath

2016

Journal of Sound and Vibration

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Section: Acoustic Fieldsupporting

confidence: 87%

Section: Flow Fieldmentioning

confidence: 99%

Section: Flow Fieldmentioning

confidence: 99%

See 1 more Smart Citation

Impact of chevron spacing and asymmetric distribution on supersonic jet acoustics and flow

Heeb

Gutmark

Kailasanath

2016

Journal of Sound and Vibration

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“…In this case the BBSAN dominates the spectrum in the upstream and sideline direction and partly in the downstream. The measurement contains strong screech tones and these have been shown (Andre et al 45 ) to have strong effects on BBSAN. Except in the upstream direction, the BBSAN peak is not correctly predicted and is often higher by St = 0.2 to 0.3.…”

Section: Resultsmentioning

confidence: 96%

Towards a Comprehensive Model of Jet Noise using an Acoustic Analogy and Steady RANS Solutions

Miller

2013

19th AIAA/CEAS Aeroacoustics Conference

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An acoustic analogy is developed to predict the noise from jet flows. It contains two source models that independently predict the noise from turbulence and shock wave shear layer interactions. The acoustic analogy is based on the Euler equations and separates the sources from propagation. Propagation effects are taken into account by calculating the vector Green's function of the linearized Euler equations. The sources are modeled following the work of Tam and Auriault, Morris and Boluriaan, and Morris and Miller. A statistical model of the two-point cross-correlation of the velocity fluctuations is used to describe the turbulence. The acoustic analogy attempts to take into account the correct scaling of the sources for a wide range of nozzle pressure and temperature ratios. It does not make assumptions regarding fine-or large-scale turbulent noise sources, selfor shear-noise, or convective amplification. The acoustic analogy is partially informed by three-dimensional steady Reynolds-Averaged Navier-Stokes solutions that include the nozzle geometry. The predictions are compared with experiments of jets operating subsonically through supersonically and at unheated and heated temperatures. Predictions generally capture the scaling of both mixing noise and BBSAN for the conditions examined, but some discrepancies remain that are due to the accuracy of the steady RANS turbulence model closure, the equivalent sources, and the use of a simplified vector Green's function solver of the linearized Euler equations. Nomenclature AsConstant associated with the dilatation term IntroductionThis paper presents an acoustic analogy for jet noise that is based on the Euler equations. The model contains equivalent sources for the turbulent mixing noise and the broadband shock-associated noise (BB-SAN). The comprehensive model development is based on two separate acoustic analogies, one for the mixing noise and the other for the BBSAN. The evaluation of the comprehensive analogy or the summation of the spectral density of the two independent analogies results in a prediction for total jet noise. These models are designed for a wide range of Mach numbers and temperature ratios. In the context of this theory there are no assumptions of shear-, self-, large-scale, or fine-scale noise sources or spectra.The acoustic analogy for turbulent mixing noise is inspired by the work of Morris and Farassat, 1 Morris and Boluriaan, 2 Tam and Auriault, 3 and physical measurements. The equivalent sources of the acoustic analogy consist of the dilatation and unsteady forces per unit mass. The dilatation term is consistent with that of Tam and Auriault 3 and the unsteady forces per unit mass are equivalent to those of Morris and Boluriaan.2 These choices of terms allow for the acoustic intensity to scale with increasing jet Mach number and temperature. The acoustic analogy for BBSAN is the model of Morris and Miller. 4 A statistical model of the two-point cross-correlation of the turbulent velocity fluctuations describes the properties of the tur...

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“…Further to the effect on screech, the introduction of the tab results in a strong increase in broadband shock associated noise (BBSAN), observed as a large hump beginning at St ¼ 0:5. André et al (2013a) demonstrate that there is an interaction between screech and broadband shock associated noise, with screech shown to attenuate and frequency shift BBSAN. Further work by André et al (2013b) shows BBSAN increases slightly upon the introduction of a tab to the jet for a similar NPR to the results presented herein.…”

Section: Effect Of Tabs On Acoustic Fieldmentioning

confidence: 93%

Visualisation of underexpanded jet flowfields in the presence of an intrusive tab

Johnston

Edgington-Mitchell

2015

J Vis

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This paper investigates the influence of a single intrusive tab has on the flowfield of a supersonic jet. When a tab is added to the jet, an increase in the fundamental screech frequency is observed in acoustic spectra. High resolution schlieren imaging reveals alteration of both the shock structure and preferred instability mode in the jet. Two-point spatial correlation of schlieren images shows the transition from a lateral flapping mode to a punctuated toroid screech mode. This change in dominant instability mode produces a change in coherent structure wavelength that correlates well to the observed screech frequency shift in the acoustic data. The high quality of the schlieren images also allows the counter-rotating vortex pair produced by an individual tab to be identified. Images of the radial density gradient are used to estimate vortex pair location, and a statistical estimate for the trajectory of the vortex pair is produced. The vortex pair path identification technique shows that the path of the vortex pair is constrained close to the exit of the nozzle and increasingly variant in space with greater downstream distance. The vortex trajectory is shown to alter the sonic line and thus the spatial extent of the embedded shock structures.

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Broadband Shock-Associated Noise in Screeching and Non-Screeching Underexpanded Supersonic Jets

Cited by 85 publications

References 36 publications

Impact of chevron spacing and asymmetric distribution on supersonic jet acoustics and flow

Impact of chevron spacing and asymmetric distribution on supersonic jet acoustics and flow

Towards a Comprehensive Model of Jet Noise using an Acoustic Analogy and Steady RANS Solutions

Visualisation of underexpanded jet flowfields in the presence of an intrusive tab

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