Analytical predictions and measurements of the noise radiated from supersonic coaxial jets

Dahl, Milo D.; Papamoschou, Dimitri

doi:10.2514/3.14448

Cited by 11 publications

(13 citation statements)

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“…This is shown in figures 3(d) and 3(e). Dahl & Papamoschou (2000) reported that the similarity spectra fitted their measured coaxial jet noise spectra well. Viswanathan (2002Viswanathan ( , 2004 provided extensive comparisons between the similarity spectra and his measurements over a large range of subsonic Mach numbers and temperature ratios.…”

Section: Introductionmentioning

confidence: 82%

The sources of jet noise: experimental evidence

Tam¹,

et al. 2008

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The primary objective of this investigation is to determine experimentally the sources of jet mixing noise. In the present study, four different approaches are used. It is reasonable to assume that the characteristics of the noise sources are imprinted on their radiation fields. Under this assumption, it becomes possible to analyse the characteristics of the far-field sound and then infer back to the characteristics of the sources. The first approach is to make use of the spectral and directional information measured by a single microphone in the far field. A detailed analysis of a large collection of far-field noise data has been carried out. The purpose is to identify special characteristics that can be linked directly to those of the sources. The second approach is to measure the coherence of the sound field using two microphones. The autocorrelations and cross-correlations of these measurements offer not only valuable information on the spatial structure of the noise field in the radial and polar angle directions, but also on the sources inside the jet. The third approach involves measuring the correlation between turbulence fluctuations inside a jet and the radiated noise in the far field. This is the most direct and unambiguous way of identifying the sources of jet noise. In the fourth approach, a mirror microphone is used to measure the noise source distribution along the lengths of high-speed jets. Features and trends observed in noise source strength distributions are expected to shed light on the source mechanisms. It will be shown that all four types of data indicate clearly the existence of two distinct noise sources in jets. One source of noise is the fine-scale turbulence and the other source is the large turbulence structures of the jet flow. Some of the salient features of the sound field associated with the two noise sources are reported in this paper.

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Section: Introductionmentioning

confidence: 82%

The sources of jet noise: experimental evidence

Tam¹,

et al. 2008

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“…The spectral levels are corrected assuming that the nozzle throat area HW = 1 m 2 and that the measurement distance r = 20 m [5]. The horizontal axis indicates the Strouhal number based on the jet velocity U and the nozzle throat height H. As was shown in the previous work [5], the F-spectrum and the G-spectrum [8][9][10][11] can fit the experimentally observed spectra. While shock structures are observed at the downstream part of the nozzle throat, their effect on the far-field noise spectra seems to be relatively small.…”

Section: Resultsmentioning

confidence: 82%

“…The coherence between these two data is indicated with isocontours, wherein the location of the sources is clearly illustrated. Panda et al [7] pointed out that the noise source measured by the Rayleigh scattering method exhibits strong directional characteristics, and they offered an explanation for the observed directional variation based on the two-noise source model [8][9][10]. These works provided essential information in terms of the behavior of the source, and these experimental evidences contribute to the important paper by Tam et al [11], wherein the behavior of the jet noise sources is clearly illustrated.…”

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confidence: 70%

Experimental Investigation of Jet Noise Sources in a Hypersonic Nozzle at Takeoff

Araki¹,

Morita²,

Takahashi³

et al. 2015

AIAA Journal

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“…They discovered that the spectral shapes from these jets had the same shape as the similarity spectra. Dahl and Papamoschou (2000) reported that the spectra from supersonic coaxial jets could also be represented by the two similarity spectra. Most recently, Viswanathan (2000Viswanathan ( , 2004 demonstrated convincingly that these two spectra also were good fits to the measured spectra of hot subsonic and supersonic jets over a fairly large range of jet operating conditions.…”

Section: Experimental Evidence In Support Of Two Turbulent Mixing Noimentioning

confidence: 99%

Engine Test Cell Aeroacoustics and Recommendations

Tam¹

2007

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The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR'S ACRONYM(S)AEDC/XRS SPONSOR/MONITOR'S REPORT NUMBER(S)Arnold Engineering Development Center/XRS Arnold AFB, TN 37389 DISTRIBUTION/AVAILABILITY STATEMENTStatement A: Approved for public release; distribution is unlimited. SUPPLEMENTARY NOTESAvailable in the Defense Technical Information Center (DTIC). ABSTRACTGround testing of turbojet engines in test cells necessarily involves very high acoustic amplitudes, often enough and severe enough that testing is interrupted and facility hardware and test articles are damaged. The acoustic response of test cells containing energetic jets is poorly understood and generally unpredictable. Nevertheless, there is a clear need to be able to predict deleterious acoustic events in advance of facility entry. A predictive capability would permit evaluating possible fixes in advance of the entry to preclude interruption of testing and damage to hardware, both of which are costly and disruptive of weapons systems program schedules. To establish the needed predictive capability, the Arnold Engineering Development Center (AEDC) is implementing a computational aeroacoustics (CAA) capability. This report by C. K. Tam is one of several steps toward that goal. Here, Tam consolidates what is presently known about the aeroacoustics of jets and flowing ducts. The material presented includes analytical and semi-empirical models of various acoustic situations as well as test data. Also included is a proposal to ameliorate a particularly damaging acoustic event referred to as "super resonance." A future report will present CAA technology appropriate for numerical solution of the flow equations as applied to jet cells. The reproducibles used in the reproduction of this report were supplied by the author. IntroductionOne of the primary objectives of this report is to provide an overview of the sources of noise in engine test cells. An engine test cell is either a closed or a partially closed system. The solid surfaces that form the cell reflect back any incident acoustic waves. Thus a test cell creates a special acoustic environment depending on its...

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Analytical predictions and measurements of the noise radiated from supersonic coaxial jets

Cited by 11 publications

References 0 publications

The sources of jet noise: experimental evidence

The sources of jet noise: experimental evidence

Experimental Investigation of Jet Noise Sources in a Hypersonic Nozzle at Takeoff

Engine Test Cell Aeroacoustics and Recommendations

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