Transition of oscillation modes of rectangular supersonic jet in screech

Suda, Hiroshi; Manning, Ted; Kaji, Shojiro

doi:10.2514/6.1993-4323

Cited by 16 publications

(25 citation statements)

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“…The frequency of symmetrical oscillation mode from Figure 7 is calculated to be about 30,000 Hz (with corresponding St symmetrical ≈ 1.508), which is twice the frequency of flapping or spanwise oscillation mode as shown in Figures 5 and 7. This phenomenon is the same as the case without shear layer swirl as reported by Han and Taghavi [13] and in the experimental results performed by other researchers [27,32]. Figure 8(e).…”

Section: Free Jet From the Plane Rectangular Nozzle With Swirling Shesupporting

confidence: 89%

“…Previous experimental studies indicate that swirl has large-scale effects on flowfields such as jet growth, mixing enhancement, flame size, shape, stability, and combustion intensity [26,27,32,33]. Also computational methods have been applied in finding a control strategy for mixing enhancement and noise reduction while the mechanism and phenomena of mixing and shockassociated noise in supersonic jets are examined [7,17,22].…”

Section: Introductionmentioning

confidence: 99%

“…Also computational methods have been applied in finding a control strategy for mixing enhancement and noise reduction while the mechanism and phenomena of mixing and shockassociated noise in supersonic jets are examined [7,17,22]. Supersonic jets issuing from convergent-divergent nozzles were examined experimentally by Suda et al [32] with a plane rectangular nozzle with high aspect ratio to simulate two-dimensional jets. Two modes of jet oscillations, namely flapping and symmetrical oscillation modes ( f symmetrical ≈ 2f flapping ) were observed in their results.…”

Section: Introductionmentioning

confidence: 99%

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Passive Control of Supersonic Rectangular Jets through Boundary Layer Swirl

Han

Taghavi

Farokhi

2013

Int. J. Turbo Jet-Engines

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Mixing characteristics of under-expanded supersonic jets emerging from plane and notched rectangular nozzles are computationally studied using nozzle exit boundary layer swirl as a mean of passive flow control. The coupling of the rectangular jet instability modes, such as flapping, and the swirl is investigated. A threedimensional unsteady Reynolds-Averaged Navier-Stokes (RANS) code with shock adaptive grids is utilized. For plane rectangular nozzle with boundary layer swirl, the flapping and spanwise oscillations are captured in the jet's small and large dimensions at twice the frequencies of the nozzles without swirl. A symmetrical oscillatory mode is also observed in the jet with double the frequency of spanwise oscillation mode. For the notched rectangular nozzle with boundary layer swirl, the flapping oscillation in the small jet dimension and the spanwise oscillation in the large jet dimension are observed at the same frequency as those without boundary layer swirl. The mass flow rates in jets at 11 and 8 nozzle heights downstream of the nozzles increased by nearly 25% and 41% for the plane and notched rectangular nozzles respectively, due to swirl. The axial gross thrust penalty due to induced swirl was 5.1% for the plane and 4.9% for the notched rectangular nozzle.

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Section: Free Jet From the Plane Rectangular Nozzle With Swirling Shesupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Passive Control of Supersonic Rectangular Jets through Boundary Layer Swirl

Han

Taghavi

Farokhi

2013

Int. J. Turbo Jet-Engines

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“…Suda et al [61] report visualizations from a rectangular jet which is undergoing anti-symmetric flapping oscillations about the long cross-sectional axis. The jet contains a single dominant screech source centered about the third shock cell, as is typical of rectangular jets of high aspect ratio.…”

Section: Shock-cell Structure and Motionmentioning

confidence: 99%

“…Staging has been observed over a broad range of operating conditions, including in rectangular jets [61], and the dominant modes have been classified [29]. But staging has been shown to exhibit a great sensitivity to facility design, such as the size and placement of surfaces at the nozzle exit [29].…”

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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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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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