Advances in Understanding Supersonic Jet Screech: Review and Perspective

Raman, Ganesh

doi:10.1016/s0376-0421(98)00002-5

Cited by 176 publications

(134 citation statements)

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“…This phase of shear layer development occurs above the shock cell pattern, where instability-shock interaction generates screech. Further downstream, away from the main screech noise sources [7,8], the instability modes decay and generate a turbulent kinetic energy cascade to higher frequencies and wavenumbers, where kinetic energy is dissipated at the Kolmogorov length scale. A fully developed turbulent flow sets up downstream of the shock-shear layer interaction region, the latter being the established screech noise source mechanism.…”

Section: Numerical Methods 31 Governing Equationsmentioning

confidence: 99%

“…A similar compressible effect in the predicted flow of the over-expanded jet may likewise influence the growth rate of the instabilities and the shear flow mean spread. In an asymmetric B screech mode [7,8] the presence of the flapping plane is a more dominant effect in determining the shear layer mean growth and the jet features a faster spreading rate when screech is enhanced.…”

Section: Over-expanded Jet: Mean Flowmentioning

confidence: 99%

“…Measurements [5,2,3] for a Mach 2 supersonic nozzle jet are reviewed in Seiner [6]. A review by Raman [7,8] covers sonic nozzle screech and more complex nozzle geometries. The details of the instability mode interaction at a shock are reported by Westley & Woolley [9] and by Panda [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…Raman [7,8]). The source of jet screech noise is described by Powell [4] as the interaction of the convected shear layer instabilities with the shock cells in jet plume.…”

Section: Introductionmentioning

confidence: 99%

“…The source of jet screech noise is described by Powell [4] as the interaction of the convected shear layer instabilities with the shock cells in jet plume. The details of such interaction and of its self-sustained feedback have been the subject of investigation over the past 40 years, yet the reliable prediction of screech amplitude remains an open challenge [7,8]. Further advances are sought in the modelling of the driving flow instability, the jet screech noise sources and shear layer receptivity.…”

Section: Introductionmentioning

confidence: 99%

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Time accurate numerical study of turbulent supersonic jets

Rona

Zhang

2004

Journal of Sound and Vibration

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A time accurate numerical study is presented of an over-expanded Mach 2 circular turbulent jet in which the flow is assumed axisymmetric. The focus of this investigation is on the jet screech phenomenon resulting from the interaction between the large scale turbulent mixing region instabilities and the regular spacing of the shock wave-expansion system, (shock cells), in the over-expanded jet. The solution is obtained of the 'short' Time Dependent Reynolds Averaged Navier-Stokes equations (TRANS), using a two-equation, k − ω, turbulence model. The time accurate method was first calibrated for the given model geometry when the flow was fully expanded, and the resulting mean flow characteristics were compared with experimental data. The results were in broad agreement for the first ten diameters of the jet downstream of the exit. Further downstream the time averaged axial velocity decayed at a slightly faster rate than in the experiments. In an ideal inviscid fully expanded jet no shock cells would be present but in the turbulent jet calculations weak shock cells appeared which gradually died out beyond about ten diameters from the nozzle exit. The calculated non-dimensional time averaged transverse velocity profiles showed self-similarity, when allowance was made for the false origin of the shear layer, in agreement with the measured results. In the calculations for the over-expanded jet it was found, in agreement with experimental data, that the interaction between shock cell modulated instability waves and the shock-expansion system generated jet screech. It was found, as part of the screech phenomenon, that the shocks and the shock cells oscillated over a small distance which increased from the axis to a maximum within the shear layer. This shock unsteadiness resulted in the shocks being smeared when viewed in the equivalent steady flow calculations.

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Section: Numerical Methods 31 Governing Equationsmentioning

confidence: 99%

Section: Over-expanded Jet: Mean Flowmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Raman [7,8]). The source of jet screech noise is described by Powell [4] as the interaction of the convected shear layer instabilities with the shock cells in jet plume.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Time accurate numerical study of turbulent supersonic jets

Rona

Zhang

2004

Journal of Sound and Vibration

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Aerodynamic Noise

Morris¹

2010

Encyclopedia of Aerospace Engineering

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Aerodynamic noise refers to the noise generated by unsteady flow. It is also called aeroacoustics or flow noise. The noise sources can be connected with a turbulent flow, as in jet or boundary layer noise, or with the relative motion with respect to the observer of a steady flow, as in propeller or rotorcraft noise. Aerodynamic noise can contain both broadband and tonal components. To describe the noise generated by a turbulent flow, acoustic analogies have been developed that replace the turbulent flow by a distribution of equivalent sources. Turbulent flow noise can also be predicted using direct numerical simulations of the unsteady flow and the noise it generates. This chapter provides an overview of both propulsive and non‐propulsive system noise. The former systems include jets, fans, and propellers. The latter is generally referred to as airframe noise, and includes the noise generated by high lift devices, such as flaps and slats, and landing gear noise. Noise generated by the turbulent boundary layer and trailing edge noise also falls into the category of airframe noise. Though the sources of aerodynamic noise are generally nonlinear, the propagation of the sound they generate is usually a linear phenomenon. The exceptions include, multiple pure tone (buzz‐saw) noise in turbomachinery, the propagation of noise from very high speed jets, such as those found in military fighter aircraft, and sonic boom.

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Propulsion System Noise: Jet

Bailly

Bogey

2010

Encyclopedia of Aerospace Engineering

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Jet noise remains one of the dominant contributions of aircraft noise at take‐off and thus is a major inhibitor of the growth of air transport, refer to the discussion about aircraft noise sources in Challenges and Opportunities in the Next Two Decades of Aerospace Engineering of the present part. It has been also identified as a serious problem for noise pollution from the beginning of commercial jet flights in the 1950s. Development of reliable predictions for subsonic and supersonic jet noise is directly linked to our understanding of turbulent shear‐flows. In this section, the physics and modelling levels are presented for subsonic and shock‐containing supersonic jets. The importance of providing accurate descriptions for real jets, in order to give insights into flow control and noise reduction design, is also emphasized and illustrated.

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Advances in Understanding Supersonic Jet Screech: Review and Perspective

Cited by 176 publications

References 0 publications

Time accurate numerical study of turbulent supersonic jets

Time accurate numerical study of turbulent supersonic jets

Aerodynamic Noise

Propulsion System Noise: Jet

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