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Book Simulation of Supersonic Jet Noise with the Adaptation of Overflow Cfd Code and Kirchhoff Surface Integral

Download or read book Simulation of Supersonic Jet Noise with the Adaptation of Overflow Cfd Code and Kirchhoff Surface Integral written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-19 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: An acoustic prediction capability for supersonic axisymmetric jets was developed on the basis of OVERFLOW Navier-Stokes CFD (Computational Fluid Dynamics) code of NASA Langley Research Center. Reynolds-averaged turbulent stresses in the flow field are modeled with the aid of Spalart-Allmaras one-equation turbulence model. Appropriate acoustic and outflow boundary conditions were implemented to compute time-dependent acoustic pressure in the nonlinear source-field. Based on the specification of acoustic pressure, its temporal and normal derivatives on the Kirchhoff surface, the near-field and the far-field sound pressure levels are computed via Kirchhoff surface integral, with the Kirchhoff surface chosen to enclose the nonlinear sound source region described by the CFD code. The methods are validated by a comparison of the predictions of sound pressure levels with the available data for an axisymmetric turbulent supersonic (Mach 2) perfectly expanded jet. Kandula, Max and Caimi, Raoul and Steinrock, T. (Technical Monitor) Kennedy Space Center NASA/TM-2001-210263, NAS 1.15:210263

Book Jet Noise Modeling for Supersonic Business Jet Application

Download or read book Jet Noise Modeling for Supersonic Business Jet Application written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-15 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document describes the development of an improved predictive model for coannular jet noise, including noise suppression modifications applicable to small supersonic-cruise aircraft such as the Supersonic Business Jet (SBJ), for NASA Langley Research Center (LaRC). For such aircraft a wide range of propulsion and integration options are under consideration. Thus there is a need for very versatile design tools, including a noise prediction model. The approach used is similar to that used with great success by the Modern Technologies Corporation (MTC) in developing a noise prediction model for two-dimensional mixer ejector (2DME) nozzles under the High Speed Research Program and in developing a more recent model for coannular nozzles over a wide range of conditions. If highly suppressed configurations are ultimately required, the 2DME model is expected to provide reasonable prediction for these smaller scales, although this has not been demonstrated. It is considered likely that more modest suppression approaches, such as dual stream nozzles featuring chevron or chute suppressors, perhaps in conjunction with inverted velocity profiles (IVP), will be sufficient for the SBJ. Stone, James R. and Krejsa, Eugene A. and Clark, Bruce J. Glenn Research Center NAS3-00178; WBS-22-781-30-12

Book The Generation and Radiation of Supersonic Jet Noise Theory of turbulence generated jet noise noise radiation from upstream sources and combustion noise

Download or read book The Generation and Radiation of Supersonic Jet Noise Theory of turbulence generated jet noise noise radiation from upstream sources and combustion noise written by and published by . This book was released on 1972 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Development of Computational Aeroacoustics Code for Jet Noise and Flow Prediction

Download or read book Development of Computational Aeroacoustics Code for Jet Noise and Flow Prediction written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-09-27 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Accurate prediction of jet fan and exhaust plume flow and noise generation and propagation is very important in developing advanced aircraft engines that will pass current and future noise regulations. In jet fan flows as well as exhaust plumes, two major sources of noise are present: large-scale, coherent instabilities and small-scale turbulent eddies. In previous work for the NASA Glenn Research Center, three strategies have been explored in an effort to computationally predict the noise radiation from supersonic jet exhaust plumes. In order from the least expensive computationally to the most expensive computationally, these are: 1) Linearized Euler equations (LEE). 2) Very Large Eddy Simulations (VLES). 3) Large Eddy Simulations (LES). The first method solves the linearized Euler equations (LEE). These equations are obtained by linearizing about a given mean flow and the neglecting viscous effects. In this way, the noise from large-scale instabilities can be found for a given mean flow. The linearized Euler equations are computationally inexpensive, and have produced good noise results for supersonic jets where the large-scale instability noise dominates, as well as for the tone noise from a jet engine blade row. However, these linear equations do not predict the absolute magnitude of the noise; instead, only the relative magnitude is predicted. Also, the predicted disturbances do not modify the mean flow, removing a physical mechanism by which the amplitude of the disturbance may be controlled. Recent research for isolated airfoils' indicates that this may not affect the solution greatly at low frequencies. The second method addresses some of the concerns raised by the LEE method. In this approach, called Very Large Eddy Simulation (VLES), the unsteady Reynolds averaged Navier-Stokes equations are solved directly using a high-accuracy computational aeroacoustics numerical scheme. With the addition of a two-equation turbulence model and the use of a relatively c...

Book The Aeroacoustics of Supersonic Coaxial Jets

    The Aeroacoustics of Supersonic Coaxial Jets

    Book Details:
  • Author : National Aeronautics and Space Administration (NASA)
  • Publisher : Createspace Independent Publishing Platform
  • Release : 2018-07-23
  • ISBN : 9781723430411
  • Pages : 184 pages

Download or read book The Aeroacoustics of Supersonic Coaxial Jets written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-23 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Instability waves have been established as the dominant source of mixing noise radiating into the downstream arc of a supersonic jet when the waves have phase velocities that are supersonic relative to ambient conditions. Recent theories for supersonic jet noise have used the concepts of growing and decaying linear instability waves for predicting radiated noise. This analysis is extended to the prediction of noise radiation from supersonic coaxial jets. Since the analysis requires a known mean flow and the coaxial jet mean flow is not described easily in terms of analytic functions, a numerical prediction is made for its development. The Reynolds averaged, compressible, boundary layer equations are solved using a mixing length turbulence model. Empirical correlations are developed for the effects of velocity and temperature ratios and Mach number. Both normal and inverted velocity profile coaxial jets are considered. Comparisons with measurements for both single and coaxial jets show good agreement. The results from mean flow and stability calculations are used to predict the noise radiation from coaxial jets with different operating conditions. Comparisons are made between different coaxial jets and a single equivalent jet with the same total thrust, mass flow, and exit area. Results indicate that normal velocity profile jets can have noise reductions compared to the single equivalent jet. No noise reductions are found for inverted velocity profile jets operated at the minimum noise condition compared to the single equivalent jet. However, it is inferred that changes in area ratio may provide noise reduction benefits for inverted velocity profile jets. Dahl, Milo D. Glenn Research Center AEROACOUSTICS; COAXIAL FLOW; GAS JETS; JET AIRCRAFT NOISE; NOISE PREDICTION (AIRCRAFT); NOISE REDUCTION; SUPERSONIC JET FLOW; COMPUTATIONAL FLUID DYNAMICS; FLOW STABILITY; MACH NUMBER; MIXING LENGTH FLOW THEORY; TEMPERATURE RATIO; VELOCITY DISTRIBUTION...

Book Update on Supersonic Jet Noise Research at Nasa

Download or read book Update on Supersonic Jet Noise Research at Nasa written by Brenda Henderson and published by BiblioGov. This book was released on 2013-06 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: An update on jet noise research conducted in the Fundamental Aeronautics and Integrated Systems Research Programs was presented. Highlighted research projects included those focused on the development of prediction tools, diagnostic tools, and noise reduction concepts.

Book Interaction of Sound from Supersonic Jets with Nearby Structures

Download or read book Interaction of Sound from Supersonic Jets with Nearby Structures written by and published by . This book was released on 1997 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Jet Aeroacoustics

    Jet Aeroacoustics

    Book Details:
  • Author : National Aeronautics and Space Adm Nasa
  • Publisher : Independently Published
  • Release : 2019
  • ISBN : 9781792791574
  • Pages : 34 pages

Download or read book Jet Aeroacoustics written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2019 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Progress associated with research in (1) physics and prediction of turbulent mixing noise from supersonic jets, and (2) numerical simulation of supersonic jet noise is reported. Tam, Christopher Langley Research Center NASA-CR-203579, NAS 1.26:203579 NAG1-1776...

Book Predictions of Supersonic Jet Mixing and Shock Associated Noise Compared with Measured Far Field Data

Download or read book Predictions of Supersonic Jet Mixing and Shock Associated Noise Compared with Measured Far Field Data written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-22 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: Codes for predicting supersonic jet mixing and broadband shock-associated noise were assessed using a database containing noise measurements of a jet issuing from a convergent nozzle. Two types of codes were used to make predictions. Fast running codes containing empirical models were used to compute both the mixing noise component and the shock-associated noise component of the jet noise spectrum. One Reynolds-averaged, Navier-Stokes-based code was used to compute only the shock-associated noise. To enable the comparisons of the predicted component spectra with data, the measured total jet noise spectra were separated into mixing noise and shock-associated noise components. Comparisons were made for 1/3-octave spectra and some power spectral densities using data from jets operating at 24 conditions covering essentially 6 fully expanded Mach numbers with 4 total temperature ratios. Dahl, Milo D. Glenn Research Center JET MIXING FLOW; JET AIRCRAFT NOISE; SUPERSONIC JET FLOW; AERODYNAMIC NOISE; NOISE MEASUREMENT; NOISE SPECTRA; FLUID JETS; MACH NUMBER; PREDICTIONS; SHOCK WAVES; TEMPERATURE RATIO