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Jet Noise Modeling For Coannular Nozzles Including The Effects Of Chevrons
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Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721942343 Total Pages :212 pages Book Rating :4.9/5 (423 download)
Book Synopsis Jet Noise Modeling for Coannular Nozzles Including the Effects of Chevrons by : National Aeronautics and Space Administration (NASA)
Download or read book Jet Noise Modeling for Coannular Nozzles Including the Effects of Chevrons written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-27 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Development of good predictive models for jet noise has always been plagued by the difficulty in obtaining good quality data over a wide range of conditions in different facilities.We consider such issues very carefully in selecting data to be used in developing our model. Flight effects are of critical importance, and none of the means of determining them are without significant problems. Free-jet flight simulation facilities are very useful, and can provide meaningful data so long as they can be analytically transformed to the flight frame of reference. In this report we show that different methodologies used by NASA and industry to perform this transformation produce very different results, especially in the rear quadrant; this compels us to rely largely on static data to develop our model, but we show reasonable agreement with simulated flight data when these transformation issues are considered. A persistent problem in obtaining good quality data is noise generated in the experimental facility upstream of the test nozzle: valves, elbows, obstructions, and especially the combustor can contribute significant noise, and much of this noise is of a broadband nature, easily confused with jet noise. Muffling of these sources is costly in terms of size as well as expense, and it is particularly difficult in flight simulation facilities, where compactness of hardware is very important, as discussed by Viswanathan (Ref. 13). We feel that the effects of jet density on jet mixing noise may have been somewhat obscured by these problems, leading to the variable density exponent used in most jet noise prediction procedures including our own. We investigate this issue, applying Occam s razor, (e.g., Ref. 14), in a search for the simplest physically meaningful model that adequately describes the observed phenomena. In a similar vein, we see no reason to reject the Lighthill approach; it provides a very solid basis upon which to build a predictive procedure, as we believe we dem
Book Synopsis Jet Noise Modeling for Coannular Nozzles Including the Effects of Chevrons by :
Download or read book Jet Noise Modeling for Coannular Nozzles Including the Effects of Chevrons written by and published by . This book was released on 2003 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721139750 Total Pages :106 pages Book Rating :4.1/5 (397 download)
Book Synopsis Jet Noise Modeling for Supersonic Business Jet Application by : National Aeronautics and Space Administration (NASA)
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 Synopsis Air Transport and Operations by : R. Curran
Download or read book Air Transport and Operations written by R. Curran and published by IOS Press. This book was released on 2012 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the proceedings of the joint conference held in Delft, the Netherlands inJune 2012, incorporating the 3rd International Air Transport Operations Symposium ATOS, the 3rd Association of Scientific Development in Air Traffic Management in Europe ASDASeminar, the 6th International Meeting for Aviation Products Support Processes IMAPP and the 2012Complex World Seminar. The book includes the majority of academic papers presented at the conference, and provides a wide overview of the issues currently of importance in the world of air transport.pIOS Press is an international science, technical and medical publisher
Book Synopsis AIAA Aerospace Sciences Meeting and Exhibit, 42nd by :
Download or read book AIAA Aerospace Sciences Meeting and Exhibit, 42nd written by and published by . This book was released on 2004 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Flight Effects on the Aerodynamic and Acoustic Characteristics of Inverted Profile Coannular Nozzles by : Hilary Kozlowski
Download or read book Flight Effects on the Aerodynamic and Acoustic Characteristics of Inverted Profile Coannular Nozzles written by Hilary Kozlowski and published by . This book was released on 1978 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721832385 Total Pages :36 pages Book Rating :4.8/5 (323 download)
Book Synopsis Acoustic Efficiency of Azimuthal Modes in Jet Noise Using Chevron Nozzles by : National Aeronautics and Space Administration (NASA)
Download or read book Acoustic Efficiency of Azimuthal Modes in Jet Noise Using Chevron Nozzles written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-24 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The link between azimuthal modes in jet turbulence and in the acoustic sound field has been examined in cold, round jets. Chevron nozzles, however, impart an azimuthal structure on the jet with a shape dependent on the number, length and penetration angle of the chevrons. Two particular chevron nozzles, with 3 and 4 primary chevrons respectively, and a round baseline nozzle are compared at both cold and hot jet conditions to determine how chevrons impact the modal structure of the flow and how that change relates to the sound field. The results show that, although the chevrons have a large impact on the azimuthal shape of the mean axial velocity, the impact of chevrons on the azimuthal structure of the fluctuating axial velocity is small at the cold jet condition and smaller still at the hot jet condition. This is supported by results in the azimuthal structure of the sound field, which also shows little difference in between the two chevron nozzles and the baseline nozzle in the distribution of energy across the azimuthal modes measured. Brown, Clifford A. and Bridges, James Glenn Research Center NASA/TM-2006-214364, E-15640, AIAA Paper 2006-2654
Book Synopsis 41st AIAA Aerospace Sciences Meeting & Exhibit by :
Download or read book 41st AIAA Aerospace Sciences Meeting & Exhibit written by and published by . This book was released on 2003 with total page 606 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Philosophical Transactions of the Royal Society by :
Download or read book Philosophical Transactions of the Royal Society written by and published by . This book was released on 2007 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Free-jet Acoustic Investigation of High-radius-ratio Coannular Plug Nozzles by :
Download or read book Free-jet Acoustic Investigation of High-radius-ratio Coannular Plug Nozzles written by and published by . This book was released on 1984 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Method for Predicting the Noise Levels of Coannular Jets with Inverted Velocity Profiles by : J. W. Russell
Download or read book A Method for Predicting the Noise Levels of Coannular Jets with Inverted Velocity Profiles written by J. W. Russell and published by . This book was released on 1979 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: A coannular jet was equated with a single stream equivalent jet with the same mass flow, energy, and thrust. The acoustic characteristics of the coannular jet were then related to the acoustic characteristics of the single jet. Forward flight effects were included by incorporating a forward exponent, a Doppler amplification factor, and a Strouhal frequency shift. Model test data, including 48 static cases and 22 wind tunnel cases, were used to evaluate the prediction method. For the static cases and the low forward velocity wind tunnel cases, the spectral mean square pressure correlation coefficients were generally greater than 90 percent, and the spectral sound pressure level standard deviation were generally less than 3 decibels. The correlation coefficient and the standard deviation were not affected by changes in equivalent jet velocity. Limitations of the prediction method are also presented.
Book Synopsis 40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit July 11-14, 2004, Fort Lauderdale, FL.: 04-3306 - 04-3349 by :
Download or read book 40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit July 11-14, 2004, Fort Lauderdale, FL.: 04-3306 - 04-3349 written by and published by . This book was released on 2004 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effect of Multiple-nozzle Geometry on Jet Noise Generation by : Vern G. Rollin
Download or read book Effect of Multiple-nozzle Geometry on Jet Noise Generation written by Vern G. Rollin and published by . This book was released on 1961 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Static and wind tunnel near-field/far-field jet noise measurements from model scale single-flow baseline and suppressor nozzles by : Carl Lewis Jaeck
Download or read book Static and wind tunnel near-field/far-field jet noise measurements from model scale single-flow baseline and suppressor nozzles written by Carl Lewis Jaeck and published by . This book was released on 1977 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Vital Role of Shock-cell and Mach disk in Noise Production of Jet Engines by : Gibin Raju
Download or read book Vital Role of Shock-cell and Mach disk in Noise Production of Jet Engines written by Gibin Raju and published by GRIN Verlag. This book was released on 2018-07-30 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: Master's Thesis from the year 2018 in the subject Engineering - Aerospace Technology, grade: 3.64, University of Cincinnati, language: English, abstract: The aim of this thesis is to discuss the vital role of shock-cell and Mach disk in noise production of jet engines. This study focuses on calculation of shock-cell spacing and Mach disk from various configuration of C-D Nozzles using Shadowgraph technique and detailing on how it varies with the test conditions. In the past three decades, the air traffic has nearly increased by about 40% and have always called for alternative propulsion techniques to replace or support the current traditional propulsion methodology in order to travel longer distances in shorter frame of time. In the light of current demand, the thesis draws motivation from increase in noise levels due to technological advancements of meeting higher specific thrust thus, achieving higher efficiency. The thesis emphasizes on the study of shock-cell noise by developing a complete view of the shock-cell structure and associated parameters with an imperfectly expanded supersonic jet on CD Nozzles over range of under-expanded, design and over-expanded operating conditions. In the entire thesis study, the heated jets from the different C-D Nozzle are analyzed for proper visualization for the shock-cell structure. Shadowgraph is used in current study as it offers very high flexibility and acts as an excellent technique for visualizing the shock diamond exhaust structure and turbulent eddies. A systematic analysis has been performed to quantify the shadowgraph data through semantic video analysis and measured the shock-cell spacing over different temperature ratios (TR) and nozzle pressure ratios (NPR). Circular, rectangular and method of characteristics (MOC) convergent-divergent nozzles of 1.5 design Mach number with and without plates were tested to interpret the results. The data recorded during the experiment was processed to obtain an averaged image. Further, the averaged images were utilized to compute the shock-cell spacing of each nozzle. The computed shock-cell spacing is compared over the theoretical shock-cell length using empirical formula to validate the results. A good match has been established between theoretical and experimental results for the tested nozzles expect for over-expanded operating conditions.
Author :United States. National Aeronautics and Space Administration. Scientific and Technical Information Office Publisher : ISBN 13 : Total Pages :356 pages Book Rating :4.:/5 (317 download)
Book Synopsis Acoustic Tests of Duct-burning Turbofan Jet Noise Simulation by : United States. National Aeronautics and Space Administration. Scientific and Technical Information Office
Download or read book Acoustic Tests of Duct-burning Turbofan Jet Noise Simulation written by United States. National Aeronautics and Space Administration. Scientific and Technical Information Office and published by . This book was released on 1978 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt: The results of a static acoustic and aerodynamic performance, model-scale test program on coannular unsuppressed and multielement fan suppressed nozzle configurations are summarized. The results of the static acoustic tests show a very beneficial interaction effect. When the measured noise levels were compared with the predicted noise levels of two independent but equivalent conical nozzle flow streams, noise reductions for the unsuppressed coannular nozzles were of the order of 10 PNdB; high levels of suppression (8 PNdB) were still maintained even when only a small amount of core stream flow was used. The multielement fan suppressed coannular nozzle tests showed 15 PNdB noise reductions and up to 18 PNdB noise reductions when a treated ejector was added. The static aerodynamic performance tests showed that the unsuppressed coannular plug nozzles obtained gross thrust coefficients of 0.972, with 1.2 to 1.7 percent lower levels for the multielement fan-suppressed coannular flow nozzles. For the first time anywhere, laser velocimeter velocity profile measurements were made on these types of nozzle configurations and with supersonic heated flow conditions. Measurements showed that a very rapid decay in the mean velocity occurs for the nozzle tested.
Book Synopsis Intelligent Manufacturing and Energy Sustainability by : P. H. V. Sesha Talpa Sai
Download or read book Intelligent Manufacturing and Energy Sustainability written by P. H. V. Sesha Talpa Sai and published by Springer Nature. This book was released on 2023-12-29 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book includes best selected, high-quality research papers presented at the International Conference on Intelligent Manufacturing and Energy Sustainability (ICIMES 2023) held at the Department of Mechanical Engineering, Malla Reddy College of Engineering & Technology (MRCET), Hyderabad, India, during June 23–24, 2023. It covers topics in the areas of automation, manufacturing technology, and energy sustainability and also includes original works in the intelligent systems, manufacturing, mechanical, electrical, aeronautical, materials, automobile, bioenergy, and energy sustainability.
