Harmonics of Jet Screech Tones

Tam, Christopher K. W.; Parrish, Sarah; Viswanathan, K.

doi:10.2514/1.j052850

Cited by 58 publications

(21 citation statements)

References 34 publications

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“…= 1.49 in Ref. [31]. The far-field OASPL also agrees well with measurement data, and the impact of the screech tone and the second harmonic tone is clearly shown in these distributions.…”

Section: A Noise Distributions In Both Near Field and Far Fieldsupporting

confidence: 85%

Numerical Study of Noise Characteristics in Overexpanded Jet Flows

Liu¹,

Corrigan²,

Kailasanath³

et al. 2015

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Standard Form 298 (Rev. 8-98)Prescribed by ANSI Std. Z39.18Public 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 this collection of information. Noise characteristics in shock-containing jets at an overexpanded jet condition have been investigated. Total temperature ratios of 1.0 (cold), 2.0, and 3.0 are considered. The cold jet is a highly screeching jet. Frequency-wavenumber Fourier analysis is employed to examine the wave characteristics of pressure waves along the lip line and also along a near-field conical surface. It is found that the radiating portion of the pressure wave intensity increases with the jet temperature, but the hydrodynamic portion is much less sensitive to the change of the jet temperature. The near-field noise intensity associated with the Mach wave radiation is observed over a large axial distance, and the Mach wave radiation extends to much higher frequencies in heated jets. The peak radiation direction in the cold jet is dominated by the axisymmetric mode, but the directions around the sideline show a much weaker azimuthal dependence. Furthermore, the axial locations of lip-line pressure peak intensities at the screech frequency are near the axial locations of shock-cell tips. A reinforcing loop between upstream/downstream propagating waves and the induced shock-cell coherent oscillatory motion is observed in the highly screeching jet. The formation of this reinforcing loop requires a match of the peak phase velocities between upstream and downstream propagating waves. This phase velocity match exists in the highly screeching cold jet, but not in the weakly screeching heated jets. It appears that the phase velocity match that sustains the reinforcing loop is important to the screech generation, and the phase velocity mismatch in heated jets is believed to be an important cause of the screech intensity reduction. REPORT TYPE 1. REPORT DATE (DD-MM-YYYY) TITLE AND SUBTITLE AUTHOR(S) PERFORMING ORGANIZATION REPORT NUMBER PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S ACRONYM(S) 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S REPORT NUMBER(S)

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“…= 1.49 in Ref. [31]. The far-field OASPL also agrees well with measurement data, and the impact of the screech tone and the second harmonic tone is clearly shown in these distributions.…”

Section: A Noise Distributions In Both Near Field and Far Fieldsupporting

confidence: 85%

Numerical Study of Noise Characteristics in Overexpanded Jet Flows

Liu¹,

Corrigan²,

Kailasanath³

et al. 2015

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“…In addition the noise radiation cannot be seen in the direction of 90 degrees. These features are similar to axisymmetric jet [4].…”

Section: Directivity Of Density Wavessupporting

confidence: 57%

“…It is well known that the screech is the narrow-band noise with high frequency and it has multiple modes. Tam [4] examined the generation mechanism and the direction of screech in case of the jet issuing from a circular nozzle. And it has shown that the Mach number and the size of cell affect the characteristics of the screech, by comparison with Norum's experimental results [5].…”

Section: Introductionmentioning

confidence: 99%

A Numerical Study on Jet Structure and Noise Emission of Underexpanded Radial Jet

Nojima¹,

Sakakibara²,

Endo³

et al. 2019

OJFD

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In this study, an underexpanded radial jet issuing from a small gap between two circular tubes facing each other is investigated numerically. Radial jet is formed, for example, downstream of high-pressure valves in piping system and of poppet valves in engines, and causes many industrial problems such as the noise generation and the fatigue failure of structure. In this study, the jet issuing from a small gap between two tubes with same diameter is numerically simulated. The flow field is assumed to be axisymmetric against the central axis of tubes and to be symmetric against the intermediate plane between the exits of two tubes. The axisymmetric Euler equations are solved using symmetric TVD (Total Variation Diminishing) scheme. The effects of nozzle pressure ratio and of diameter of circular tubes on the structure and the behavior of jets are examined. Typical cell structure of underexpanded jet appears in radial jet and the length of cell becomes smaller in downstream region because the jet spreads radially like a disc. The length and width of first cell are larger with higher nozzle pressure ratio. Many vortices are generated one after another near the jet boundary and move downstream, which cause the oscillation of jet. Outside of jet, two types of density waves are observed. One of them propagates toward the nozzle (toward the upstream region) and the other propagates in opposite direction. Focusing on the pressure change caused by the former waves, which is related to well-known screech, dominant frequency obtained by FFT analysis was found to become lower with higher pressure ratio and smaller diameter of tube.

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“…where 60 recently recommended to take K = 0.9 which yields L * 1 st shock = 2.6 and matches with the simulation. The dimensionless supersonic region mean length can be estimated with the Mach number profile on the centerline, leading to L * sonic ≃ 21.…”

Section: Centerline Propertiesmentioning

confidence: 70%

Accurate simulation of the noise generated by a hot supersonic jet including turbulence tripping and nonlinear acoustic propagation

et al. 2019

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A procedure to accurately simulate a free hot supersonic jet and its associated noise, which uses simultaneously a turbulence tripping method and a two-way coupling between a flow solver and a nonlinear acoustic solver, is proposed in this study. A Mach 3.1 overexpanded hot jet is computed via a large-eddy simulation by solving the filtered Navier-Stokes equations with a finite volume method on unstructured grids. The resulting noise is propagated in the far field by solving the full Euler equations with a high-order discontinuous Galerkin method on unstructured grids. The full convergent-divergent nozzle is explicitly included in the computational domain thanks to the unstructured flow solver. Both a refined grid and a geometrical boundary layer tripping in the convergent are used to get highly disturbed turbulent conditions at the nozzle lips. The flow field appears to agree with the expected turbulence behavior and the available experimental data. The jet development shows significant improvement compared to similar past simulations. The far field acoustic levels are finely recovered at most of observation angles. An analysis of the acoustic near and far fields is then performed. The studied conditions lead to strong shock-associated noise and Mach wave emission. The spatio-frequency and azimuthal content of the acoustic field is described in order to identify the main noise properties. A particular noise component, different from screech tones and radiating upstream like Mach waves, is highlighted. Nonlinear propagation effects are finally quantified through specific metrics. They are found significant in both the near and the far fields which justifies the use of a nonlinear acoustic solver.

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Harmonics of Jet Screech Tones

Cited by 58 publications

References 34 publications

Numerical Study of Noise Characteristics in Overexpanded Jet Flows

Numerical Study of Noise Characteristics in Overexpanded Jet Flows

A Numerical Study on Jet Structure and Noise Emission of Underexpanded Radial Jet

Accurate simulation of the noise generated by a hot supersonic jet including turbulence tripping and nonlinear acoustic propagation

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