Screech tones from rectangular jets with spanwise oblique shock-cell structures

Raman, Ganesh

doi:10.2514/6.1996-643

Cited by 39 publications

(55 citation statements)

References 20 publications

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“…According to the stability theory, the description of the instability wave in space and 45 time can be decomposed into a product of terms corresponding to the shear-layernormal variation (the eigenfunction), the streamwise growth, and the streamwise convection:…”

Section: Inflow Forcingmentioning

confidence: 99%

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A numerical investigation of sound generation in supersonic jet screech

Manning

Lele

2000

6th Aeroacoustics Conference and Exhibit

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including gathering and maintaining the data needed, and completing and reviewing the collection of information. Send collection of information, including suggestions for reducing this burden, to Washington Headquarters Services Davis Highway, Suite 1 204, Arlington, VA 22202-4302, and fcV-tW 0Vf*si?of Management and Budget, Paper« AGENCY USE ONLY (Leave blank)2. REPORT DATE 11/29/00 REPORV-AFRL-SR-BL-TR-00-öürtl i. mm UM I i:a lUVbHbU 04/01/98-'09/30/00 TITLE AND SUBTITLE(U) A Numerical Investigation of Sound Generation in Supersonic JET Screech AUTHOR(S)Ted A. Manning and Sanjiva K. Lele FUNDING NUMBERSF49620-98-1-0355 The noise : i supersonic jet flows is due in part to the interaction between jet instability waves and the jet shock-cell structure. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)DEPARTMENTThe emitted shock-cell noise re-excites certain instability wave modes at the nozzle lip and causes resonant feedback to occur. This feedback resonance, known as supersonic jet screech, causes the jet to flap violently at discrete frequencies and generate very strong, narrow-banded tones. Jet screech is a source of acoustic fatigue in the tail and nozzle structures of supersonic aircraft. It is therefore important that methods for predicting the screech amplitude be developed.In the present research we investigate the screech sound generation process, particularly for high amplitude instability waves. We isolate the interaction of an unsteady shear layer with a single oblique shock. To obtain an overall understanding of the phenomenon with fewest simplifications, we study this problem through the numerical solution of the Navier-Stokes equations. We then consider idealizations to obtain a similar but wider range of results with specially linearbed Euler equations. These results motivate the use of geometric acoustics to describe the screech generation process. The Navier-Stokes and Euler simulations have revealed important details about the interaction process, how the acoustic field results, and why the screech is so loud. AbstractThe noise of supersonic jet flows is due in part to the interaction between jet instability waves and the jet shock-cell structure. If no counter-measures are taken, the emitted shock-cell noise will re-txcite certain instability wave modes at the nozzle lip and cause resonant feedback to occur. This feedback resonance, known as supersonic jet screech, causes the jet to flap violently at discrete frequencies and generate very strong, narrow-banded tones. Jet screech has been shown to be a source of acoustic fatigue in the tail and nozzle structures of supersonic aircraft. It is therefore important that methods for predicting the screech amplitude be developed. While comprehensive screech models will require taking all elements of the feedback loop into consideration, a basic understanding of each element in isolation will also be necessary. Screech sound generation is one such ...

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Section: Inflow Forcingmentioning

confidence: 99%

“…The twin jet configuration has been studied [49,50,55] and has been shown to result in screech of increased intensity. The effects of unusual nozzle geometry on screech have been studied by several [29,34,45,72,75], including beveled, elliptical, and triangular nozzle geometries.…”

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confidence: 99%

A numerical investigation of sound generation in supersonic jet screech

Manning

Lele

2000

6th Aeroacoustics Conference and Exhibit

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“…Figure 1.34 shows a comparison of the numerical results of (1.51) and the experimental measurements of Raman (1996). There is excellent agreement between predictions and measurements over the Mach number range of 1.1 < M j < 1.8.…”

Section: Fundamental Screech Tone Frequencymentioning

confidence: 77%

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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“…Screech tones, relating to jet noise generation, may also have a detrimental effect on aircraft structures. Raman [14] showed that the level of screech tones altered depending on a span-wise nozzle exit geometry. Rectangular jets have also been used for combustors [15,16] and they lead to enhancement of the combustion performance due to axis switching associated with self-induced vortex ring deformations.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional shock wave distortion in shock-square vortex loop interaction

Ukai

Zare‐Behtash

Kontis

et al. 2016

Experimental Thermal and Fluid Science

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Abstract:Understanding of the three-dimensional shock wave-vortex loop interaction phenomena plays a key role in noise reduction. This study focuses on the three-dimensional shock wave distortion and propagation phenomena in a near-field supersonic jet. Shock-square vortex loop interaction was experimentally investigated in a square cross-sectional open-end shock wave generating tube at an incident shock Mach number of 1.39 ± 0.05. A square vortex loop impinged on a reflected shock wave from a wall located in front of the nozzle end. The planar reflected shock wave transforms into either a concave or convex distorted shape due to the opposing high-speed flow emitted from the nozzle corner. The convex shaped shock wave scatters towards the outside of the vortex loop, whereas the concave one converges towards the centre of the vortex loop. The concave shaped shock wave results in shock wave focusing. In shock-square vortex loop interaction, the shock wave is locally focused along the axis of the nozzle corner. Keywords:Shock wave interaction; square vortex loop; shock wave focusing 2

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Screech tones from rectangular jets with spanwise oblique shock-cell structures

Cited by 39 publications

References 20 publications

A numerical investigation of sound generation in supersonic jet screech

A numerical investigation of sound generation in supersonic jet screech

Engine Test Cell Aeroacoustics and Recommendations

Three-dimensional shock wave distortion in shock-square vortex loop interaction

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