Author: D.W. Forsyth
Publisher:
ISBN:
Category :
Languages : en
Pages : 59

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Author: Jay C. Hardin
Publisher: Springer Science & Business Media
ISBN: 1461383420
Category : Science
Languages : en
Pages : 525

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Computational aeroacoustics is rapidly emerging as an essential element in the study of aerodynamic sound. As with all emerging technologies, it is paramount that we assess the various opportuni ties and establish achievable goals for this new technology. Essential to this process is the identification and prioritization of fundamental aeroacoustics problems which are amenable to direct numerical siIn ulation. Questions, ranging from the role numerical methods play in the classical theoretical approaches to aeroacoustics, to the correct specification of well-posed numerical problems, need to be answered. These issues provided the impetus for the Workshop on Computa tional Aeroacoustics sponsored by ICASE and the Acoustics Division of NASA LaRC on April 6-9, 1992. The participants of the Work shop were leading aeroacousticians, computational fluid dynamicists and applied mathematicians. The Workshop started with the open ing remarks by M. Y. Hussaini and the welcome address by Kristin Hessenius who introduced the keynote speaker, Sir James Lighthill. The keynote address set the stage for the Workshop. It was both an authoritative and up-to-date discussion of the state-of-the-art in aeroacoustics. The presentations at the Workshop were divided into five sessions - i) Classical Theoretical Approaches (William Zorumski, Chairman), ii) Mathematical Aspects of Acoustics (Rodolfo Rosales, Chairman), iii) Validation Methodology (Allan Pierce, Chairman), iv) Direct Numerical Simulation (Michael Myers, Chairman), and v) Unsteady Compressible Flow Computa tional Methods (Douglas Dwoyer, Chairman).

Author: Jay C. Hardin
Publisher:
ISBN:
Category : Aerodynamic noise
Languages : en
Pages : 412

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Author: N. Sarigul-Klijn
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Harvey H. Hubbard
Publisher:
ISBN:
Category : Aerodynamic noise
Languages : en
Pages : 620

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Author: A-21 Aircraft Noise Measurement Aviation Emission Modeling
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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This document has been determined to contain basic and stable technology which is not dynamic in nature.

Author: National Aeronautics and Space Administration NASA
Publisher:
ISBN: 9781731262387
Category :
Languages : en
Pages : 114

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This report presents the derivation of a frequency domain theory and working equations for radiation of propeller harmonic noise in the presence of angular inflow. In applying the acoustic analogy, integration over the tangential coordinate of the source region is performed numerically, permitting the equations to be solved without approximation for any degree of angular inflow. Inflow angle is specified in terms of yaw, pitch, and roll angles of the aircraft. Since these can be arbitrarily large, the analysis applies with equal accuracy to propellers and helicopter rotors. For thickness and loading, the derivation is given in complete detail with working equations for near and far field. However, the quadrupole derivation has been carried only far enough to show feasibility of the numerical approach. Explicit formulas are presented for computation of source elements, evaluation of Green's functions, and location of observer points in various visual and retarded coordinate systems. The resulting computer program, called WOBBLE has been written in FORTRAN and follows the notation of this report very closely. The new theory is explored to establish the effects of varying inflow angle on axial and circumferential directivity. Also, parametric studies were performed to evaluate various phenomena outside the capabilities of earlier theories, such as an unsteady thickness effect. Validity of the theory was established by comparison with test data from conventional propellers and Prop Fans in flight and in wind tunnels under a variety of operating conditions and inflow angles. Hanson, Donald B. and Parzych, David J. Unspecified Center AEROACOUSTICS; NOISE PREDICTION (AIRCRAFT); PROPELLER FANS; PROPELLER NOISE; ACOUSTIC FREQUENCIES; COMPUTER PROGRAMS; DIRECTIVITY; FAR FIELDS; GREEN'S FUNCTIONS; NEAR FIELDS; PROP-FAN TECHNOLOGY; PROPELLER BLADES; QUADRUPOLES...

Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 232

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Author: Ilene J Busch-Vishniac
Publisher:
ISBN:
Category : Noise control
Languages : en
Pages : 520

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Author:
Publisher:
ISBN:
Category : Aerodynamic noise
Languages : en
Pages : 282

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