The Experts below are selected from a list of 99 Experts worldwide ranked by ideXlab platform
Roldão Rocha - One of the best experts on this subject based on the ideXlab platform.
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Black hole acoustics in the minimal geometric deformation of a de Laval Nozzle
The European Physical Journal C, 2017Co-Authors: Roldão RochaAbstract:The correspondence between sound waves, in a de Laval Propelling Nozzle, and quasinormal modes emitted by brane-world black holes deformed by a 5D bulk Weyl fluid are here explored and scrutinized. The analysis of sound waves patterns in a de Laval Nozzle in the laboratory, reciprocally, is here shown to provide relevant data about the 5D bulk Weyl fluid and its on-brane projection, comprised by the minimal geometrically deformed compact stellar distribution on the brane. Acoustic perturbations of the gas fluid flow in the de Laval Nozzle are proved to coincide with the quasinormal modes of black holes solutions deformed by the 5D Weyl fluid, in the geometric deformation procedure. Hence, in a phenomenological Eötvös–Friedmann fluid brane-world model, the realistic shape of a de Laval Nozzle is derived and its consequences studied.
Daniel Jonas Dezan - One of the best experts on this subject based on the ideXlab platform.
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Turbojet Engine Noise Prediction Utilizing Empirical Methods
Volume 2: Aircraft Engine; Coal Biomass and Alternative Fuels; Cycle Innovations, 2013Co-Authors: João Roberto Barbosa, Daniel Jonas DezanAbstract:This work deals with the prediction of noise generated by gas turbines, which includes engines being designed. One has in mind the fulfillment of the ever-increasing concerns with environment, in particular noise. Analytical and empirical methods have been focused by researchers and industry, although only empirical prediction methods are utilized in this work, for the calculation of the one-third octave band sound pressure levels associated to the main engine noise sources. The methodology for the calculation of the engine noise has been combined with performance and design computational programs to evaluate the noise emitted by each engine component and, by proper combination, the engine total noise. A newly designed and manufactured 5 kN/1.2 MW turbojet engine serves as the basis for the noise prediction. For the study, the main noise sources are: compressor, combustor, turbine and Propelling Nozzle. In terms of the overall sound pressure level, OASPL, are compatible with the noise produced by similar engines. The noise predictions are performed at engine design speeds in the range of 100% down to 70% of the design speed (28,150 rpm). The engine has not run yet, but it is expected that measured noise will be available in the near future. However, it is important to emphasize that all prediction models used to evaluate the radiated noise from the engine were validated. The engine operating conditions were calculated using a high fidelity engine simulator developed to provide the data used in this study. The methods to estimate the one-third octave band sound pressure levels are reported in NASA TM-195480, SAE ARP-876D, NASA-ANOPP and ESDU Item 98019. No atmospheric attenuation and ground reflection were considered in this work.© 2013 ASME
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Combustor and Single-Stream Jet Noise Prediction for a Newly Designed Turbojet Engine by Using Semi-Empirical Methods
Volume 3: Cycle Innovations; Education; Electric Power; Fans and Blowers; Industrial and Cogeneration, 2012Co-Authors: João Roberto Barbosa, Daniel Jonas DezanAbstract:Research is being carried out at the Technological Institute of Aeronautics to provide the support for the design of high performance gas turbines, including noise prediction by means of theoretical and empirical methods. Emphasis is given to new engines noise prediction, to anticipate problems at very early design stage and to take the necessary actions to guarantee that the engine noise is below the imposed limits. Noise prediction is part of the high fidelity engine performance prediction computer program, which provides the designer, at any time during the design phases, with information on the noise levels generated by each component and by the engine. Research indicates that the combustor and the Propelling Nozzle are major noise sources, so that these two components of a turbojet engine were dealt with in this work. The far-field one-third octave band sound pressure levels, (SPL), and overall sound pressure level (OASPL) are calculated, for several observer positions and engine rotational speeds. A 5 kN turbojet engine under development serves as the basis for the noise prediction. The influence of the observer position on SPL and OASPL for steady engine operation, as well as the effect of the engine rotational speeds on the engine noise generated by the combustor and the Propelling Nozzle are presented, which are in agreement with the noise of similar engines. Ground reflection and atmospheric attenuation were not considered. A high fidelity engine performance prediction computer code incorporates the noise prediction methodology whose results are reported in this paper.Copyright © 2012 by ASME
J. Reid - One of the best experts on this subject based on the ideXlab platform.
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PRICE I6S. od. NETThe Effect of a Cylindrical Shroud on the Performance of a Stationary Convergent Nozzle
2012Co-Authors: J. ReidAbstract:Summary. One possible method of reducing jet noise at take-off is the use of an ejector in which the Propelling Nozzle discharges into a shroud and thereby induces a secondary flow. The present report describes an experiment on the aerodynamics of such systems. The primary Nozzle was axisymmetric and convergent and the shrouds were cylindrical with faired convergent entries. The stagnation temperatures of the primary and secondary streams were equal and the secondary flow was entrained from the ambient static atmosphere. Ratios of jet total pressure to ambient static pressure ranged from 1.0 to 2.0. A systematic study was made of the effect of ejector length, ejector area ratio and jet pressure ratio on the ejector performance. This was specified in terms of the ratio of secondary to primary mass flow, the velocity profile at the shroud outlet and the thrust. The variation in static pressure along the shroud wall and the distribution of total and static pressure within a shroud were also determined. No acoustic measurements were made. The results are in fair agreement with the predictions of a simplified ejector theory which assumes uniform one-dimensional flow at the entry and outlet of the shroud and negligible skin-friction losses. The optimum shroud tested gave 15 % more thrust than the unshrouded primary Nozzle at a jet pressure ratio of 2 ' 0
João Roberto Barbosa - One of the best experts on this subject based on the ideXlab platform.
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Turbojet Engine Noise Prediction Utilizing Empirical Methods
Volume 2: Aircraft Engine; Coal Biomass and Alternative Fuels; Cycle Innovations, 2013Co-Authors: João Roberto Barbosa, Daniel Jonas DezanAbstract:This work deals with the prediction of noise generated by gas turbines, which includes engines being designed. One has in mind the fulfillment of the ever-increasing concerns with environment, in particular noise. Analytical and empirical methods have been focused by researchers and industry, although only empirical prediction methods are utilized in this work, for the calculation of the one-third octave band sound pressure levels associated to the main engine noise sources. The methodology for the calculation of the engine noise has been combined with performance and design computational programs to evaluate the noise emitted by each engine component and, by proper combination, the engine total noise. A newly designed and manufactured 5 kN/1.2 MW turbojet engine serves as the basis for the noise prediction. For the study, the main noise sources are: compressor, combustor, turbine and Propelling Nozzle. In terms of the overall sound pressure level, OASPL, are compatible with the noise produced by similar engines. The noise predictions are performed at engine design speeds in the range of 100% down to 70% of the design speed (28,150 rpm). The engine has not run yet, but it is expected that measured noise will be available in the near future. However, it is important to emphasize that all prediction models used to evaluate the radiated noise from the engine were validated. The engine operating conditions were calculated using a high fidelity engine simulator developed to provide the data used in this study. The methods to estimate the one-third octave band sound pressure levels are reported in NASA TM-195480, SAE ARP-876D, NASA-ANOPP and ESDU Item 98019. No atmospheric attenuation and ground reflection were considered in this work.© 2013 ASME
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Combustor and Single-Stream Jet Noise Prediction for a Newly Designed Turbojet Engine by Using Semi-Empirical Methods
Volume 3: Cycle Innovations; Education; Electric Power; Fans and Blowers; Industrial and Cogeneration, 2012Co-Authors: João Roberto Barbosa, Daniel Jonas DezanAbstract:Research is being carried out at the Technological Institute of Aeronautics to provide the support for the design of high performance gas turbines, including noise prediction by means of theoretical and empirical methods. Emphasis is given to new engines noise prediction, to anticipate problems at very early design stage and to take the necessary actions to guarantee that the engine noise is below the imposed limits. Noise prediction is part of the high fidelity engine performance prediction computer program, which provides the designer, at any time during the design phases, with information on the noise levels generated by each component and by the engine. Research indicates that the combustor and the Propelling Nozzle are major noise sources, so that these two components of a turbojet engine were dealt with in this work. The far-field one-third octave band sound pressure levels, (SPL), and overall sound pressure level (OASPL) are calculated, for several observer positions and engine rotational speeds. A 5 kN turbojet engine under development serves as the basis for the noise prediction. The influence of the observer position on SPL and OASPL for steady engine operation, as well as the effect of the engine rotational speeds on the engine noise generated by the combustor and the Propelling Nozzle are presented, which are in agreement with the noise of similar engines. Ground reflection and atmospheric attenuation were not considered. A high fidelity engine performance prediction computer code incorporates the noise prediction methodology whose results are reported in this paper.Copyright © 2012 by ASME
Da Rocha Roldao - One of the best experts on this subject based on the ideXlab platform.
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Black hole acoustics in the minimal geometric deformation of a de Laval Nozzle
'Springer Science and Business Media LLC', 2017Co-Authors: Da Rocha RoldaoAbstract:The correspondence between sound waves, in a de Laval Propelling Nozzle, and quasinormal modes emitted by brane-world black holes deformed by a 5D bulk Weyl fluid are here explored and scrutinised. The analysis of sound waves patterns in a de Laval Nozzle at a laboratory, reciprocally, is here shown to provide relevant data about the 5D bulk Weyl fluid and its on-brane projection, comprised by the minimal geometrically deformed compact stellar distribution on the brane. Acoustic perturbations of the gas fluid flow in the de Laval Nozzle are proved to coincide to the quasinormal modes of black holes solutions deformed by the 5D Weyl fluid, in the geometric deformation procedure. Hence, in a phenomenological E\"otv\"os-Friedmann fluid brane-world model, the realistic shape of a de Laval Nozzle is derived and its consequences studied.Comment: 7 pages, 3 figure
