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Sunday, August 2, 2020 | History

2 edition of Circumferentially segmented duct liners optimized for axisymmetric and standing-wave sources found in the catalog.

Circumferentially segmented duct liners optimized for axisymmetric and standing-wave sources

Willie R Watson

Circumferentially segmented duct liners optimized for axisymmetric and standing-wave sources

by Willie R Watson

  • 101 Want to read
  • 13 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:
  • Standing waves,
  • Soundproofing,
  • Air ducts -- Noise control

  • Edition Notes

    StatementWillie R. Watson
    SeriesNASA technical paper -- 2075
    ContributionsUnited States. National Aeronautics and Space Administration. Scientific and Technical Information Branch
    The Physical Object
    Pagination47 p. :
    Number of Pages47
    ID Numbers
    Open LibraryOL14933231M

    The liner is installed in the test duct with the active segment facing the source. The original design of the hybrid liner was directed at controlling modes (4,O) and (4,1) at Hz. The "upstream" active segment redirects energy for more effective absorption by the passive segment. The turbulence characteristics of an axisymmetric wake shed by a very slender body at Mach 3 have been measured with the hot‐wire anemometer. The region covered began at transition, located immediately downstream of the model, and ended about virtual (momentum) wake diameters downstream. By using computer‐aided corrections to the anemometer frequency Cited by:

    sources while outer wall has been cooled isothermally. They have used finite difference scheme to study variation of Nusselt number with Darcy-Rayleigh number, aspect ratio and radii ratio. Nithiarasu, Seetharamu, Sundarajan [7] have worked on natural convection in axisymmetric porous cavity using finite element method. Sankar, Kim, Lopez and. 4 31 time-dependent boundaries, although some closed-form or theoretical solutions have been 32 developed for excavations in rheological rock [8, 9, 10]. However, in all these works the excavation 33 is assumed to take place instantaneously, i.e. the process of excavation in the tunnel cross-section is 34 ignored and only the longitudinal advancement of the tunnel face is .

    “The far downstream evolution of the high Reynolds number axisymmetric wake behindadisk. Part1. Singlepointstatistics”, Prepared for submission to the Journal of Fluid Mechanics. Paper 9 “The far downstream evolution of the high Reynolds number axisymmetric wake behind a disk. Part Size: 7MB.   Wall shear stress and velocity in a turbulent axisymmetric boundary layer. Anthony Wietrzak (a1) and If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about R. A. Scaling of wall shear stress fluctuations in a turbulent duct by:


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Circumferentially segmented duct liners optimized for axisymmetric and standing-wave sources by Willie R Watson Download PDF EPUB FB2

The circumferentially segmented liner: in which K~ is the complex axial wave number and P (r,8) is the acoustic pressure eigenfunction for the circumferentially segmented liner.

Solutions for the eigen- function pR(r,e) and for the axial wave number are developed in the following sec- tion. Circumferentially segmented duct liners optimized for axisymmetric and standing-wave sources. 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.

Results show that for some frequencies and duct lengths, circumferentially segmented liners scatter energy equally between a higher and lower order circumferential wave number.

Studies for higher order spinning-mode sources show that an optimized segmented liner with a hard-wall/soft-wal admittance variation representing an optimum configuration gives better performance than an optimized uniform : W.

Watson. The lining impedance is axially segmented uniform, but varies circumferentially. The sound pressure is expanded in term of rigid duct modes and an additional function that carries the information about the impedance by: Impingement of Water Droplets on an Ellipsoid with Fineness Ratio 5 in Axisymmetric Flow [Robert G.

Dorsch] on *FREE* shipping on qualifying offers. Results show that for some frequencies and duct lengths, circumferentially segmented liners scatter energy equally between a higher and lower order circumferential wave number.

[18] Lester H. and Posey J. W., “ Optimal One-Section and Two-Section Circular Sound-Absorbing Duct Liners for Plane-Wave and Monopole Sources Without Flow,” NASA TN D, Google Scholar [19] Watson W.

R., “ Circumferentially Segmented Duct Liners Optimized for Axisymmetric and Standing Wave Sources,” NASA TPAuthor: Emre Özkaya, Nicolas R. Gauger, Junis Abdel Hay, Frank Thiele.

An optimized, four-segmented liner with impedance segments in a checkerboard arrangement is found to be inferior to an optimized spanwise segmented liner. This optimized spanwise segmented liner.

Multiple pure tone noise radiation from a supersonic rotor propagating in an acoustically treated duct. WATSON NASA TP Noise suppression characteristics of peripherally seg- mented duct liners.

WATSON NASA TP Circumferentially segmented duct liners optimized for axisymmetric and standing-wave sources. by: 8. Watson, “ Circumferentially segmented duct liners optimized for axisymmetric and standing wave sources,” NASA ().

Google Scholar; C. Fuller, “ Propagation and radiation of sound from flanged circular ducts with circumferentially varying wall admittances, I: semi-infinite ducts,” J.

Sound by: 9. In this paper a numerical algorithm is described for solving the boundary value problem associated with axisymmetric, inviscid, incompressible and irrota-tional flow with a circumferentially arranged cascade of aerofoils placed in the : Vasos Pavlika. NUMERICAL ANALYSIS OF AXISYMMETRIC TURBULENT SWIRLING FLOW IN CIRCULAR PIPE by Aleksandar S.

]O]I]*, Milan R. LE^I], and Svetislav M. ^ANTRAK Faculty of Mechanical Engineering, University of Belgrade, Belgrade, Serbia Original scientific paper DOI: TSCIC In this paper, turbulent swirling flow in circular pipe is numerically File Size: KB.

would someone could tell me the difference between Axisymmetric and Axisymmetric Swirl. How does the solver calculates the pressure force and mass of rigid body in these 2D case. To do the calculation, you need know specific area and volume.

Hi I use 2D axisymmetric swirl model for 2d-simmulation of annular couette flow. I define the fluid source in a moving reference frame with certain 2d-axisymmetric- swirl flow -- CFD Online Discussion Forums.

The liner properties are assumed to be given by a distribution of locally reacting impedances. Without significant loss of generality, the distribution may be assumed axially segmented, i.e.

the impedance is set piecewise constant along the duct, while being arbitrarily variable along the circumference of each segment (see Fig.

Given the complex modal input amplitudes at one end of the hard-walled duct Cited by: Modeling Axisymmetric Flows with Swirl or Rotation. As discussed in Sectionyou can solve a 2D axisymmetric problem that includes the prediction of the circumferential or swirl assumption of axisymmetry implies that there are no circumferential gradients in the flow, but that there may be non-zero circumferential velocities.

Generally the material properties and loadings are symmetric with respect to the axis. In such situations axisymmetric solid with axisymmetric load- ing can be employed. If the loading is axisymmetric, the dis- placement vector has two components in the radial and axial directions.

The governing equations are derived by circumferentially averaging the three-dimensional (3D) Navier-Stokes equations, which are solved using a time marching finite volume approach. Both Euler throughflow model and Navier-Stokes (N-S) throughflow model are employed to investigate the performance and flow fields of a highly loaded transonic single Cited by: 1.

Full text of "NASA Technical Reports Server (NTRS) Aeronautical Engineering: A continuing bibliography, cumulative index" See other formats. These parameters are the non-dimensionalised ratio between applied moment and bending stiffness and the ratio between inner and outer radius. Furthermore, it is noted that free-free boundary conditions and circumferentially distributed bending moments do not break the circular symmetry of the annular disk.

Symmetry test at the circular duct's exit 73 Horizontal symmetry test at the duct's exit for all angles 74 Vertical symmetry at the duct's exit for all angles 75 Mean axial velocity isovel contours for 10° 76 Mean axial velocity isovel contours for 15° 77 Mean axial velocity isovel contours for ° 78 Computational Study of Axisymmetric Off-Design Nozzle Flows [Teryn Dalbello, Nasa Technical Reports Server (Ntrs), Et Al] on *FREE* shipping on qualifying offers.

Computational Fluid Dynamics (CFD) analyses of axisymmetric circular-arc boattail nozzles operating off-design at transonic Mach numbers have been completed.

These computations Cited by:   Axisymmetric jet manipulated using two unsteady minijets - Volume - H. Yang, Y. Zhou Skip to main content Accessibility help We use cookies to distinguish you from other users and to provide you with a better experience on our by: