Download or read book Determining Model of Sonic Boom Propogation Through a Turbulent Atmosphere written by National Aeronautical Establishment (Canada) and published by . This book was released on 1972 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Deterministic Model of Sonic Boom Propagation Through a Turbulent Atmosphere written by B. H. K. Lee and published by 1972.. This book was released on 1972 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The propagation of a weak normal shock wave through a turbulent atmosphere is studied in terms of an idealized model. The turbulent field is assumed to be weak and represented by the superposition of two inclined shear waves of opposite inclination to the mean flow. The resulting flow is of a cellular nature. The cells are rectangular in shape and the sense of rotation of the flow alternates from cell to cell. If the angles made by the normal of the incident shear waves with the direction of the mean flow are greater than some critical value an exponentially decaying pressure wave is generated behind the shock. 'Spiked' or rounded' waveforms are obtained by adding or subtracting this pressure wave from the steady state pressure field. An illustrative example for a mean flow Mach number of 1.0005 is considered. (Author).

Download or read book Sonic Boom Propagation Through a Realistic Turbulent Atmosphere written by Patrice Marc Boulanger and published by . This book was released on 1994 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High speed Research 1994 Sonic Boom Workshop written by David A. McCurdy and published by . This book was released on 1994 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 3D Simulation of Acoustical Shock Waves Propagation Through a Turbulent Atmosphere Application to Sonic Boom written by David Luquet and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis deals with the effects of atmospheric turbulence on the propagation of acoustical shock waves. These effects are of major interest for applications such as sonic boom, buzz saw noise or thunder. A numerical one-way method is developed to model and to simulate three-dimensional nonlinear propagation of acoustical shock waves in a moving heterogeneous medium. It relies on a split-step approach that permits to take into account efficiently the different involved physical mechanisms. To tackle realistic 3D problems (of order of one billion of degree of freedom), the implementation of the method is done using the parallel single program multiple data paradigm. Validity of this method is assessed using multiple test cases. The method is applied to investigate the effects of atmospheric turbulence on sonic boom propagation through the Planetary Boundary Layer. Hence, both under-track boom and boom in the shadow zone are studied for a hypersonic configuration developed in the European project ATLLAS II. Finally, the focusing of weak shock waves on a cusped caustic is simulated. It is the first study of the stability of a nonlinear caustic to flow perturbations to our knowledge.

Download or read book High Speed Research Sonic Boom Volume 1 written by and published by . This book was released on 1994 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Third Conference on Sonic Boom Research written by Ira R. Schwartz and published by . This book was released on 1971 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: Prediction methods for sonic boom generation and propagation with overpressure minimization in supersonic transport design and operation.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 440 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of Sonic boom Signatures in a Stratified Atmosphere written by Raymond L. Barger and published by . This book was released on 1968 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sonic Boom Modeling Investigation of Topographical and Atmospheric Effects written by Andrew B. Bauer and published by . This book was released on 1970 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental program was undertaken to study the effects of topographical and structural shapes on sonic boom focusing and to study the effects of atmospheric turbulence on sonic boom signatures. These effects were modeled by firing projectiles and by allowing the projectile N waves to interact with model shapes and with turbulent jets. The wave interactions were studied by means of shadowgraph pictures and microphone pressure records. The boom focusing parameters were related to the work of Ting and Pan. A canyon model showed wave amplification factors as large as 14 for a special shape and a particular wave direction of propagation. A large amount of statistical information was obtained from the turbulence interactions. This information was studied and found to be in essential agreement with the theory of Crew, but the mechanisms of the shock front breakup and of certain nonlinear features are not understood. Turbulence scaling parameters are developed and used to relate the model results to full scale. (Author).

Download or read book Second Conference on Sonic Boom Research written by Ira R. Schwartz and published by . This book was released on 1968 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of a conference on sonic boom reduction in supersonic transport flight. Topics include shock wave propagation and refraction, prediction methods for acoustic attenuation, and aerodynamic engineering aspects.

Download or read book Simulation of N wave and Shaped Supersonic Signature Turbulent Variations written by Trevor Stout and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the design paradigms for the next generation of civil supersonic aircraft targets a reduction in sonic boom amplitude and impulsivity, creating a shaped signature at the ground which is likely more acceptable to the public. The unshaped, conventional N-wave sonic boom is well known to distort due to atmospheric turbulence or wind and temperature fluctuations, randomly increasing or decreasing the loudness perceived by listeners. However, the effect of turbulence on the shaped signature is not well understood. No acoustic databases from powered, fully-shaped aircraft yet exist because these prototypes are currently in development. Thus, the present work uses a numerical model based on an augmented nonlinear KZK propagation equation and simulated shaped signatures to analyze the turbulence effects. The KZK equation accounts for absorption, nonlinearity, advection due to turbulence and resultant diffraction, as well as other propagation effects. A novel implementation of a fully time-domain solution is put forth. As is typically done in the literature, the solution to the KZK equation in two dimensions is predominantly used in the present work, though a computationally-intensive 3D algorithm is applied to a limited case. As part of the recently-completed Sonic Booms in Atmospheric Turbulence (SonicBAT) project, supersonic flyover measurement campaigns were conducted to produce the first database of its kind with acoustic data of N-waves from powered, manned aircraft and concurrent atmospheric turbulence and weather data. One objective was to provide suitable inputs for the present numerical model so that the simulated output statistics could be compared with the measured. This comparison shows reasonable agreement between the model and the measurement for most cases across a wide range of atmospheric and turbulence parameters, suggesting that the KZK model is suitable for predicting full-scale sonic boom loudness variations. Using the validated algorithm, turbulence effects on simulated shaped signatures are analyzed in many hypothetical atmospheres and compared to the effects on the N-wave, revealing that the boom shaping tends to reduce loudness variations. Finally, the prevailing use of 2D simulations in the literature and the present work is qualified by comparison to comparable 3D simulations, finding that inclusion of the third dimension somewhat augments the turbulence effects and increases the predicted probability of high-amplitude N-wave booms.

Download or read book NASA Technical Memorandum written by and published by . This book was released on 1986 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Speed Research Sonic Boom Volume 1 written by and published by . This book was released on 1992 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1973 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Laboratory Study of Subjective Response to Sonic Booms Measured at White Sands Missile Range written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-28 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Sonic Boom Simulator of the Langley Research Center was used to quantify subjective loudness response to boom signatures consisting of: (1) simulator reproductions of booms recently recorded at White Sands Missile Range; (2) idealized N-waves; and (3) idealized booms having intermediate shocks. The booms with intermediate shocks represented signatures derived from CFD predictions. The recorded booms represented those generated by F15 and T38 aircraft flyovers and represented a variety of waveforms reflecting the effects of propagation through a turbulent atmosphere. These waveforms included the following shape categories: N-waves, peaked, rounded, and U-shaped. Results showed that Perceived Level and Zwicker Loudness Level were good estimators of the loudness of turbulence modified sonic booms. No significant differences were observed between loudness responses for the several shape categories when expressed in terms of Perceived Level. Thus, Perceived Level effectively accounted for waveform differences due to turbulence. Idealized booms with intermediate shocks, however, were rated as being approximately 2.7 dB(PL) less loud than the recorded signatures. This difference was not accounted for by PL. Sullivan, Brenda M. and Leatherwood, Jack D. Langley Research Center RTOP 537-03-21-03...

Download or read book Some Effects of Flight Path and Atmospheric Variations on the Boom Propagated from a Supersonic Aircraft written by Raymond L. Barger and published by . This book was released on 1964 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Equations for the shock wave envelope and cusp line associated with the boom propagated from a supersonic aircraft are formulated in terms of the moving-trihedral coordinate system for flight in a uniform atmosphere and also in an atmosphere with a linear sound-speed gradient. Ray-tube theory is used to calculate the lateral distribution of boom intensity in an atmosphere with a linear sound-speed gradient and also to investigate the effect of a general wind and sound-speed gradient on the ground-track intensity. The relative effects of wind and temperature gradient are treated. The mechanism of focusing by winds and by ground structures are discussed qualitatively.