Download or read book Supersonic Coaxial Jet Noise Predictions written by Milo D. Dahl and published by . This book was released on 1995 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Supersonic Coaxial Jets Noise Predictions and Measurements written by and published by . This book was released on 1998 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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...
Download or read book SUPERSONIC COAXIAL JETS NOISE PREDICTIONS AND MEASUREMENTS NASA TM 1998 207422 JUL 6 1998 written by United States. National Aeronautics and Space Administration and published by . This book was released on 1998* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Development of a Fast Method for the Calculation of Noise from Supersonic Jets written by Andrew Thomas Merck and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The development of a high-speed jet noise prediction method that is significantly less computationally expensive than previous computationally-based methods and which provides a simple user interface is described. Several sets of far-field spectral density experimental data are decomposed into their large-scale turbulence component and the corresponding near-field wavenumber spectra are calculated. A wavepacket model is used to characterize the near-field wavenumber spectrum at the surface of the jet flow, and the wavepacket properties given by the near-field spectra at various frequencies and operating conditions are found using Gaussian fits. A large database is compiled from the wavepacket properties for a range of operating conditions, and the far-field jet noise is predicted using a mathematical model that combines the wavepacket model and existing models. Comparison of the wavepacket-model far-field supersonic jet noise predictions and experimental measurements are made, and the results demonstrate that the wavepacket-model results in accurate noise predictions.
Download or read book On the Prediction of the Near Field Noise of Supersonic Jets written by J. B. Ollerhead and published by . This book was released on 1967 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Supersonic Jet Noise Reductions Predicted with Increased Jet Spreading Rate written by and published by . This book was released on 1995 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Computation of Supersonic Jet Noise Under Imperfectly Expanded Conditions written by Chan M. Kim and published by . This book was released on 1993 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Generation and Radiation of Supersonic Jet Noise Append 2 Shock associated noise data written by and published by . This book was released on 1972 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Predictions of Supersonic Jet Mixing and Shock Associated Noise Compared with Measured Far Field Data written by Nasa Technical Reports Server (Ntrs) and published by BiblioGov. This book was released on 2013-07 with total page 84 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.
Download or read book An Empirical Method for Predicting the Mixing Noise Levels of Subsonic Circular and Coaxial Jets written by James W. Russell and published by . This book was released on 1984 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Empirical Source Noise Prediction Method with Application to Subsonic Coaxial Jet Mixing Noise written by W. E. Zorumski and published by . This book was released on 1982 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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...
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
Download or read book The Generation Radiation and Prediction of Supersonic Jet Noise written by and published by . This book was released on 1978 with total page 509 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented in this report forms a continuation of the fundamental studies on the generation and radiation of supersonic jet noise, reported in technical reports AFAPL-TR-72-53 (six volumes), AFAPL-TR-74-24, and AFAPL-TR-76-65 (four volumes). The total noise from a supersonic jet is taken to consist of contributions from three independent noise sources: (1) small-scale turbulent mixing noise, (2) noise from large-scale turbulence structure, and (3) shock-associated noise. The generation, radiation and prediction of each of these noise components is described in this report. In addition, the mean and turbulent flow characteristics of heated and unheated, subsonic and supersonic jets, measured by a laser velocimeter system, are also presented. Finally, a computer program for the prediction of jet noise, based on fundamental principles as far as possible at the present time, is presented and described in the form of a user's guide. A complete listing of this computer program is given in the Appendix volume (Volume 11) of this report.
Download or read book The Generation Radiation and Prediction of Supersonic Jet Noise Volume II Appendix Computer Program Listing written by B. J. Tester and published by . This book was released on 1978 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: This appendix volume presents a complete listing of the unified jet noise prediction computer program (UNIJET), developed to predict the total noise from a subsonic or supersonic jet under static conditions. In addition, a listing of the computer program (called INTEG) to predict absolute turbulent mixing noise levels at 90 deg to the jet axis, using laser velocimeter turbulence measurement, is also given. A detailed description of these two programs in the form of a user's guide is given in the main volume of this report. (Author).
Download or read book Prediction of Turbulence Generated Noise in Unheated Jets Part 1 Jeno Technical Manual Version 1 0 written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-03 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: The model-based approach, used by the JeNo code to predict jet noise spectral directivity, is described. A linearized form of Lilley's equation governs the non-causal Green s function of interest, with the non-linear terms on the right hand side identified as the source. A Reynolds-averaged Navier-Stokes (RANS) solution yields the required mean flow for the solution of the propagation Green s function in a locally parallel flow. The RANS solution also produces time- and length-scales needed to model the non-compact source, the turbulent velocity correlation tensor, with exponential temporal and spatial functions. It is shown that while an exact non-causal Green s function accurately predicts the observed shift in the location of the spectrum peak with angle as well as the angularity of sound at low to moderate Mach numbers, the polar directivity of radiated sound is not entirely captured by this Green s function at high subsonic and supersonic acoustic Mach numbers. Results presented for unheated jets in the Mach number range of 0.51 to 1.8 suggest that near the peak radiation angle of high-speed jets, a different source/Green s function convolution integral may be required in order to capture the peak observed directivity of jet noise. A sample Mach 0.90 heated jet is also discussed that highlights the requirements for a comprehensive jet noise prediction model.Khavaran, Abbas and Bridges, James and Georgiadis, NicholasGlenn Research CenterNOISE PREDICTION; TURBULENCE; JET AIRCRAFT NOISE; CONVOLUTION INTEGRALS; EXPONENTIAL FUNCTIONS; MACH NUMBER; MATHEMATICAL MODELS; SUPERSONIC SPEED
