Nozzle Shaping for Reduction of Jet Noise from Single Jets

Viswanathan, K.

doi:10.2514/6.2004-2974

Cited by 13 publications

(29 citation statements)

References 17 publications

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“…It is a three-dimensionally curved Single Expansion Ramp "SERN" type that can be thought of as an "inside out" plug where the extended tail surface of the nozzle is equivalent to the plug and was tailored for supersonic cruise pressure ratios greater than 5 ( Figure 3). The potential noise benefit of beveled nozzles had been previously examined by Viswanathan 5 .…”

Section: Nozzle Configurationsmentioning

confidence: 99%

Directivity Effects of Shaped Plumes from Plug Nozzles

Chase¹,

Garzon²,

Papamoschou

2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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A set of various shaped nozzles designed by Aerion Corporation were investigated on a reduced scale facility at University of California Irvine (UCI). Initial results on some of the configurations show great potential in directing the noise away from the relevant azimuth positions and producing significant reduction in noise levels. Flow surveys and numerical analysis have been performed to better understand the mechanisms which produce such improvement.

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Section: Nozzle Configurationsmentioning

confidence: 99%

Directivity Effects of Shaped Plumes from Plug Nozzles

Chase¹,

Garzon²,

Papamoschou

2013

51st AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

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“…For this high velocity jet with V j = 3040 ft/s, the spectral shape changes from a broad peak to a narrower peak in this angular region, resulting in the observed increase of ∼10 dB at the lower frequencies. For a progression in spectral shape and level with radiation angle for an M j = 1.0 jet at a stagnation temperature ratio of 3.2, see Figure 18 in Viswanathan [19]. Let us now compare the normalized spectra from the two microphone array locations at these three angles for the unheated and heated jets in Figures 28 and 29, respectively.…”

Section: Effect Of Source Directivitymentioning

confidence: 99%

Distributions of Noise Sources in Heated and Cold Jets: Are They Different?

Viswanathan

2010

International Journal of Aeroacoustics

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It is a distinct pleasure to write this article to honor the seminal contributions of Prof. Lilley. The impact of his theoretical expositions has been profound and the field of aeroacoustics has benefited greatly from his keen intellect. His body of research over nearly six decades encompasses early experiments on jet noise in the 1940s to the exploration of flow-generated noise in a variety of problems. I first met Prof. Lilley in person in the 1980s at Penn State, when he gave a seminar on the role of large scale structures in turbulent mixing. His kind demeanor, unprepossessing manner and affability impressed me, when as a graduate student I was carrying out my doctoral research. Prof. Lilley's work has inspired generations of researchers in aeroacoustics for nearly four decades-I am proud to state that I am one of them. His research articles, whether on the intricacies of the generation of jet noise, airframe noise, or the silent flight of the owl, are thought-provoking. I have benefited greatly from his erudite publications and direct interactions for several years. It would be remiss were I not to point out that my own experimental research on jet noise has cast serious doubt on the early theories on jet noise, which as it turns out now were based on data of questionable quality. Regardless, the thought process and the theoretical arguments adduced to explain complex phenomena spurred me (as I am sure many others) to question basic assumptions and proposed formulations. I especially treasure Prof. Lilley's long personal letters, with feedback on my research, his frank opinion, and his enjoinment to entertain multiple ideas in the interpretation of data. Above all, I will be forever grateful for his encouragement and graciousness. Prof. Lilley has always embodied the spirit of science: "Rarely is a new idea the product of a single mind. Scientists depend on each other to criticize ideas in seminars and reviews of manuscripts and research proposals. Participation in rigorous, open, scientific debate is one of the most stimulating aspects of being a scientist" (from "Scientific Teaching", by J. Handelsman, S. Miller and C. Pfund, The Wisconsin Program for Scientific Teaching, ISBN-13: 978-1-4292-0188-9,  2007 by W. H. Freeman and Company). I truly cherish the scientific engagements with Prof. Lilley; it has been enlightening and most rewarding.

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“…Drastic modification of the jet cross-section was achieved by the investigated configurations, with both elliptic and triangular shapes attained downstream. Consequently, screech was nearly eliminated with reductions in the range of [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] dB depending on the operating condition. Analysis of the streamwise velocity indicated that both the mean shock spacing and strength were reduced resulting in an increase in the broadband shock associated noise spectral peak frequency and a reduction in the amplitude, respectively.…”

Section: Introductionmentioning

confidence: 96%

“…the jet without chevrons was similar to the baseline configuration, but as the jet propagated downstream it was deflected off of the centerline in the direction opposite of the chevrons. Beveled jets are known to deflect from the centerline [19,20], but the deflection of overexpanded jets is typically in the direction of the long side of the jet. This is primarily due to inward turning of the flow at the lip of the shorter side of the bevel.…”

Section: Flow Fieldmentioning

confidence: 99%

“…Replication of this configuration was achieved by grouping six chevrons together on one side of the nozzle. Viswanathan [19] showed that a nozzle beveled at 45°was quieter than a typical nozzle for nearly all observation and azimuthal angles. Maximum overall sound pressure level (OASPL) reductions were approximately 10 dB and were seen to coincide with the longer lip.…”

Section: Introductionmentioning

confidence: 99%

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