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Thursday, July 30, 2020 | History

2 edition of Shock associated noise reduction from inverted-velocity-profile coannular jets found in the catalog.

Shock associated noise reduction from inverted-velocity-profile coannular jets

H. K. Tanna

Shock associated noise reduction from inverted-velocity-profile coannular jets

by H. K. Tanna

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  • 5 Currently reading

Published by National Aeronautics and Space Administration, Scientific and Technical Information Branch, For sale by the National Technical Information Service] in Washington, D.C, [Springfield, Va .
Written in English

    Subjects:
  • High-speed aeronautics -- Testing.,
  • Noise control.

  • Edition Notes

    StatementH.K. Tanna, C.K.W. Tam, and W.H. Brown ; prepared for Langley Research Center under contract NAS1-15971.
    SeriesNASA contractor report -- 3454., NASA contractor report -- NASA CR-3454.
    ContributionsTam, C. K. W., Brown, W. H., United States. National Aeronautics and Space Administration. Scientific and Technical Information Branch., Langley Research Center.
    The Physical Object
    Paginationiv, 156 p. :
    Number of Pages156
    ID Numbers
    Open LibraryOL17653425M

      Jet noise itself is composed of turbulent mixing noise and, in the case of imperfectly expanded jets, shock noise. Jet mixing noise is a strong characteristic of jet exhaust velocity. Consequently, noise reduction strategies are aimed at increasing the bypass ratio to lower nozzle exit velocities and designing bypass and core flows to improve. NOISE FROM SUPERSONIC COAXIAL JETS, PART 3: INVERTED VELOCITY PROFILE NOISE FROM SUPERSONIC COAXIAL JETS, PART 3: INVERTED VELOCITY PROFILE Dahl, M.D.; Morris, P.J. Journal of Sound and Vibration () (5), ­ M. D. DAHL National Aeronautics and Space Administration, Lewis Research Center, Cleveland, OH , U.S.A. AND P. .

    AIAA PAPER "The Noise Characteristics of Inverted Velocity Profile Coannular Jets" by A. M. Cargill and J. P. Duponchel ted at the 4-th AIAA Aero-acoustic Specialists conference Atlanta Georgia in October, structure during shock,6 indicating that the shock spectrum applies to com-posite structures. I have often tried to fig-ure out how the accelera-tion shock spectrum be-came so popular. It is presented in almost all mechanical engineering vibration texts and hand-books that mention shock spectrum at all. Many books and articles go into.

    Example: Known Shock Speed Ti= K pi= 1 atm vs= m/s • Given: Normal shock moving at m/s into still air ( K, 1 atm) • Find: 1. Temperature behind shock (after shock passes) 2. Velocity of gas behind shock (in “lab” reference frame) 3. Stagnation temperature before and after shock (in lab ref. frame) • Assume: Air TPG/CPG. Noise control. Here are entered general works on the reduction or elimination of noise. Works on noise in types of institutions and industries and generated by types of vehicles, machinery, equipment, etc., and efforts to reduce or eliminate it, are entered under the appropriate heading with the subdivision Noise.. See also what's at Wikipedia, your library, or elsewhere.


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Shock associated noise reduction from inverted-velocity-profile coannular jets by H. K. Tanna Download PDF EPUB FB2

Designing Clean Jet-Noise Facilities and Making Accurate Jet-Noise Measurements 30 November | International Journal of Aeroacoustics, Vol.

2, No. 3 Twin-jet screech suppression. SHOCK NOISE FROM COANNULAR JETS, PART 1 For Figure 7(a), and coannular jet was operated at inverted-velocity-profile conditions, and the noise reductions at 0 = 30are essentially due to the reduction in the jet mixing noise relative to that of the equivalent single by: An experimental and theoretical investigation of shock-associated noise of inverted-profile coannular jets is described.

For a fixed fan-stream Mach number, it is observed that the shock-associated noise often drops suddenly to a minimum as the reservoir pressure of the primary jet by: 8.

The reduction of shock-associated noise in inverted-velocity-profile coannular jets is quantified and explained by conducting extensive optical and acoustic measurements for a suitable range of outer-stream and inner-stream presure-ratio combinations, and by interpreting the measured noise results with the aid of new theoretical models.

The reduction of shock-associated noise in inverted velocity profile coannular jets is investigated and quantified by making optical and acoustic measurements as a function of outer and inner stream pressure ratio combinations and interpreting noise results with the aid of new theoretical : H.

Tanna, W. Brown and C. Tam. At this optimum condition, the coannular jet provides the maximum noise reduction relative to the equivalent single jet. The shock noise reduction can be achieved at inverted-as well as normal-velocity-profile conditions, provided the coannular jet Author: C.

Tam, W. Brown and H. Tanna. At this optimum condition, the coannular jet provides the maximum noise reduction relative to the equivalent single jet. The shock noise reduction can be achieved at inverted-as well as normal-velocity-profile conditions, provided the coannular jet.

The shock noise reduction can be achieved at inverted-as well as normal-velocity-profile conditions, provided the coannular jet is operated with the inner stream just slightly supersonic.

Analytical models for the shock structure and shock noise are developed indicate that a drastic change in the outer stream shock cell structure occurs when the inner stream increases its velocity from.

Results for inverted velocity profile jets indicate that relative maximum instability wave amplitudes and far field peak noise levels can be reduced from that of the reference jet by having higher. Effect of density on noise radiation from subsonic inverted velocity profile jets. SAROHIA and P.

MASSIER. These components are referred to as the turbulent mixing noise and the broadband shock associated noise or simply shock associated noise. The general consensus appears to be that the former is generated directly by the turbulence of the jet flow while the latter is produced by the unsteady interaction between the flow turbulence and the quasi.

Broadband shock-associated noise is a component of jet noise generated by supersonic jets operating off-design. It is characterized by multiple broadband peaks and dominates the total noise at. Shock associated noise reduction from inverted-velcoity-profile coannular jets.

Washington, D.C.: National Aeronautics and Space Administration, Scientific and Technical Information Branch; [Springfield, Va.: For sale by the National Technical Information Service], (OCoLC) Material Type. This explains the greater noise reduction, ~11 dB, in simulated flight than in the static case, ~ dB, for the C-D termina- tion, since the shock noise is amplified in flight in the forward quadrant while the jet mixing noise is generally reduced slightly (although in this particular case there is very little effect).

Shock associated noise of supersonic jets from convergent-divergent nozzles. Journal of Sound and Vibration, 81 (3)–, zbMATH CrossRef Google Scholar C. A basic understanding of the noise reduction mechanisms in shock-free inverted-velocity-profile coannular jets was studied.

Acoustic measurements are first conducted in an anechoic facility to isolate the effects of inverted velocity and inverted temperature for coannular jets having constant total thrust, mass flow rate and exit area.

To obtain physical explanations of the measured noise. of a coannular jet exhaust nozzle with an inverted velocity profile. The method equates the coannular jet to a single stream equivalent jet with the samemass flow, energy, and thrust as the coannular jet. The acoustic charac-teristics of the coannular jet are then related to the acoustic characterls-tics of the single jet.

In addition, high-radius ratio coannular plug nozzles were found to yield shock associated noise level reductions relative to a conical nozzle.

The wind tunnel aerodynamic tests showed that static and simulated flight thrust coefficient at typical takeoff conditions are quite good - up to at static conditions and at a takeoff Mach.

The shock associated noise reduction can be achieved at inverted- as well as normal-velocity-profile conditions, provided the coannular jet is operated with the primary stream just slightly supersonic. Shock Associated Noise Reduction from Inverted-Velocity-Profile Coannular Jets.

Paper presented at AIAA 7th Aeroacoustics Conference, The American. numerical simulation of broadband shock-associated noise from a circular supersonic jet Gao, J. / Li, X. / American Institute of Aeronautics and Astronautics | print version.Shock-cell noise is identified to be a potentially significant problem for advanced supersonic aircraft at takeoff.

Therefore NASA conducted fundamental Skip to main content.technique and shock velocity is measured with the optical streak camera. The shock pressure measured with the laser intensity up to x 10 14 W/cm 2 is about 25 Mbar in aluminum foils.

RESEARCH ARTICLE ISSUE NO. • NOV. - DEC. BARC NEWSLETTER 14 Direct measurement of .