Theory for Noise of Propellers in Angular Inflow with Parametric Studies and Experimental Verification PDF Download
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Author: National Aeronautics and Space Administration NASA
Publisher:
ISBN: 9781731262387
Category :
Languages : en
Pages : 114
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Book Description
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: National Aeronautics and Space Administration NASA
Publisher:
ISBN: 9781731262387
Category :
Languages : en
Pages : 114
Get Book Here
Book Description
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: Donald B. Hanson
Publisher:
ISBN:
Category : Propellers, Aerial
Languages : en
Pages : 118
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Book Description
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 556
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Book Description
Author: Rolf Radespiel
Publisher: Springer Nature
ISBN: 3030524299
Category : Technology & Engineering
Languages : en
Pages : 634
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Book Description
This book reports on the latest numerical and experimental findings in the field of high-lift technologies. It covers interdisciplinary research subjects relating to scientific computing, aerodynamics, aeroacoustics, material sciences, aircraft structures, and flight mechanics. The respective chapters are based on papers presented at the Final Symposium of the Collaborative Research Center (CRC) 880, which was held on December 17-18, 2019 in Braunschweig, Germany. The conference and the research presented here were partly supported by the CRC 880 on “Fundamentals of High Lift for Future Civil Aircraft,” funded by the DFG (German Research Foundation). The papers offer timely insights into high-lift technologies for short take-off and landing aircraft, with a special focus on aeroacoustics, efficient high-lift, flight dynamics, and aircraft design.
Author: Antonio Filippone
Publisher: Cambridge University Press
ISBN: 113978966X
Category : Technology & Engineering
Languages : en
Pages : 665
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Book Description
This book discusses aircraft flight performance, focusing on commercial aircraft but also considering examples of high-performance military aircraft. The framework is a multidisciplinary engineering analysis, fully supported by flight simulation, with software validation at several levels. The book covers topics such as geometrical configurations, configuration aerodynamics and determination of aerodynamic derivatives, weight engineering, propulsion systems (gas turbine engines and propellers), aircraft trim, flight envelopes, mission analysis, trajectory optimisation, aircraft noise, noise trajectories and analysis of environmental performance. A unique feature of this book is the discussion and analysis of the environmental performance of the aircraft, focusing on topics such as aircraft noise and carbon dioxide emissions.
Author:
Publisher:
ISBN:
Category : Mathematics
Languages : en
Pages : 1250
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Book Description
Publishes research papers in the mathematical and physical sciences. Continues: Proceedings of the Royal Society of London. Series A, Mathematical and physical sciences. Continued by: Proceedings. Mathematical, physical, and engineering sciences.
Author:
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages :
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Author:
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 1592
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Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 436
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Book Description
Author: World Bank
Publisher: World Bank Publications
ISBN: 9780821323953
Category : Business & Economics
Languages : en
Pages : 1422
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Book Description
The Republic of Korea's industrial policy has directed that nation's economy through nearly three decades of spectacular growth. But the authors of this paper maintain that this policy is showing signs of being outmoded. The time has come, the authors argue, for the Korean government to stop managing the economy's structural development and to redefine the responsibilities of business and government. Under this proposed compact, the allocation of resources would shift from the government to the private industrial and financial sectors. The transformation of the government bureaucracy from an ad hoc policy role to one of a transparent and predictable regulator is a key to the success of this undertaking. These new directions would present the government with enormous challenges. Greater competitive discipline and regulatory oversight would be required. While dealing with the complexities of the transition, the government would have to maintain macroeconomic stability and the momentum of savings and investment. For comparison, the study examines the industrial economies of France, Germany, Japan, and the United States, which underwent similar shifts.
