Rotorcraft Noise Abatement Flight Path Modeling PDF Download
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Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781723974762
Category : Science
Languages : en
Pages : 80
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Book Description
This report addresses development of a rotor state/trim modeling capability for noise modeling of decelerating rotorcraft approaches. The resulting technique employs discretization of the descent trajectory as multiple steady state segments for input to CAMRAD.Mod 1 to predict rotor states for acoustic analysis. Deceleration is included by modifying the CAMRAD.Mod 1 free flight trim options to allow trim to the specified acceleration/deceleration components.Murty, Hema and Berezin, Charles R.Langley Research CenterNOISE REDUCTION; FLIGHT PATHS; APPLICATIONS PROGRAMS (COMPUTERS); MATHEMATICAL MODELS; SIKORSKY WHIRLWIND HELICOPTER; FLIGHT TESTS; STEADY STATE; ACOUSTIC MEASUREMENT; DESCENT TRAJECTORIES; DECELERATION
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781723974762
Category : Science
Languages : en
Pages : 80
Get Book Here
Book Description
This report addresses development of a rotor state/trim modeling capability for noise modeling of decelerating rotorcraft approaches. The resulting technique employs discretization of the descent trajectory as multiple steady state segments for input to CAMRAD.Mod 1 to predict rotor states for acoustic analysis. Deceleration is included by modifying the CAMRAD.Mod 1 free flight trim options to allow trim to the specified acceleration/deceleration components.Murty, Hema and Berezin, Charles R.Langley Research CenterNOISE REDUCTION; FLIGHT PATHS; APPLICATIONS PROGRAMS (COMPUTERS); MATHEMATICAL MODELS; SIKORSKY WHIRLWIND HELICOPTER; FLIGHT TESTS; STEADY STATE; ACOUSTIC MEASUREMENT; DESCENT TRAJECTORIES; DECELERATION
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 80
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Book Description
Author:
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 132
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Book Description
Author: Mrunali Botre
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The main contribution from the current work is the enhancement of a comprehensive noise prediction system for rotorcraft and a methodology to analyze flight test procedures in the interest of understanding the noise source generation mechanisms and aid development of noise abatement procedures. This dissertation describes a rotorcraft noise prediction system and its development to incorporate time-dependent information--including trajectory, attitude, blade loads and rotor thrust--for predicting noise generated during a complex maneuver. The validation process is carried out by comparing the predicted noise levels (SELdBA, OASPL and A--weighted SPL) and processed flight test data. The examples considered are: level flight; descent flight; level turns; level, decelerating turns; and descending turns. This range of operations is considered to analyze the prediction system and understand its capabilities and deficiencies for future work. Overall the predicted noise levels were able to match the trends and levels within a 2--4 dB of that measured during the flight test. The time histories are studied in detail to understand the influence of events (such as steady flight conditions, with constant speed, roll angle or descent rate, and transient flight conditions, including roll-in and roll-out of turn, start and end of deceleration or acceleration) occurring during the flight procedure on noise levels and directivity. The key takeaways are that the noise prediction system was able to capture the noise levels but missed blade-vortex-interaction (BVI) noise directivity during some complex maneuvers. Transient maneuvers generate higher-harmonic loading and BVI noise and the intensity depends on the rate of change of flight conditions. The tail rotor not only contributes the thickness noise below the flight path but has significant contribution at sideline observer locations during a maneuver. The radiation distance and directivity have shown a stronger effect on noise levels than the harmonic noise sources. Lastly, the broadband noise dominates the A--weighted SPL for the steady maneuvers (except descent) and its importance is less during the transient flight segments. A final thing to note is that the noise generated during a 6° steady descent (the standard descent angle for approach) was much higher than any other complex procedures studied in the current work.
Author: Oleksandr Zaporozhets
Publisher: CRC Press
ISBN: 0415240662
Category : Technology & Engineering
Languages : en
Pages : 435
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Book Description
Aircraft noise has adverse impacts on passengers, airport staff and people living near airports, it thus limits the capacity of regional and international airports throughout the world. Reducing perceived noise of aircraft involves reduction of noise at source, along the propagation path and at the receiver. Effective noise control demands highly skilled and knowledgeable engineers. This book is for them. It shows you how accurate and reliable information about aircraft noise levels can be gained by calculations using appropriate generation and propagation models, or by measurements with effective monitoring systems. It also explains how to allow for atmospheric conditions, natural and artificial topography as well as detailing necessary measurement techniques.
Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781729185605
Category : Science
Languages : en
Pages : 52
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Book Description
To meet its objective of assisting the U.S. aviation industry with the technological challenges of the future, NASA must identify research areas that have the greatest potential for improving the operation of the air transportation system. To accomplish this, NASA is building an Aviation System Analysis Capability (ASAC). The Flight Track Noise Impact Model (FTNIM) has been developed as part of the ASAC. Its primary purpose is to enable users to examine the impact that quieter aircraft technologies and/or operations might have on air carrier operating efficiency at any one of 8 selected U.S. airports. The analyst selects an airport and case year for study, chooses a set of flight tracks for use in the case, and has the option of reducing the noise of the aircraft by 3, 6, or 10 decibels. Two sets of flight tracks are available for each airport: one that represents actual current conditions, including noise abatement tracks, which avoid flying over noise-sensitive areas; and a second set that offers more efficient routing. FTNIM computes the resultant noise impact and the time and distance saved for each operation on the more efficient, alternate tracks. Noise impact is characterized in three ways: the size of the noise contour footprint, the number of people living within the contours, and the number of homes located in the same contours. Distance and time savings are calculated by comparing the noise abatement flight path length to the more efficient alternate routing. Burn, Melissa and Carey, Jeffrey and Czech, Joseph and Wingrove, Earl R., III Langley Research Center NAS2-14361; RTOP 538-08-11-01...
Author: Welden E. Clark
Publisher:
ISBN:
Category :
Languages : en
Pages : 73
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Book Description
Development of a computer-aided approach to the analysis of aircraft noise as it affects communities near airports is summarized in the report. The major factors that must be described to specify the noise stimulus and the factors which appear to be relevant to description of the community-wide response to that noise are discussed and diagrammed. An approach to analysis of aircraft noise situations that involves close man-computer interaction is formulated and programming to implement this approach is described. Some illustrations of the process are presented. The major computer programs being developed will: (a) calculate perceived noise levels from octave band noise spectra; (b) calculate areas from graphical input data (maps, noise contours); (c) calculate and display noise contours for a simulated aircraft flight; (d) calculate the time pattern of noise exposure at a ground position near an aircraft flight path; and (e) calculate and assemble the noise levels occurring at multiple ground positions during a number of simulated aircraft flights. (Author).
Author: Lilia A. Abron-Robinson
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 78
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Book Description
Author: Interagency Aircraft Noise Research Panel
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 236
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Book Description
Author: Lauren Weist
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Rotorcraft are a versatile and important class of vehicles within the aerospace industry, but they experience a highly varied aerodynamic environment that causes unique acoustic conditions. These acoustics are highly tonal, and are often found to cause community annoyance. Due to this, providing acoustic considerations for rotorcraft is a necessary area of research within the industry. To aid in these considerations, this thesis addresses noise via modeling through two noise prediction systems (NPS). To account for rotorcraft acoustics in the design stage, a low fidelity NPS, the NDARC NPS, was used. For acoustic considerations of existing helicopters, the high fidelity Penn State NPS is used. The low fidelity system, the NDARC NPS, is described first. As acoustic consideration in the design stage is not often conducted, development of a rapid tool to give to a designer is paramount. The NDARC NPS was created to fill this desire, and has been further developed as a part of this thesis. The NDARC NPS was fully exercised to identify issues and improve the system. Improvements to the blade-vortex interaction model, comprised of the Beddoes wake model and Vatistas implementation of the Biot-Savart law were completed. Improvements were made to the user interface, the complete suite of example cases was improved and expanded, and the User's Manual was completed. The mid-fidelity system, known as the Penn State NPS, is used to aid in providing guidance on noise abatement procedures for existing vehicles to aid in the reduction of community annoyance.In this work, the Penn State NPS was used to conduct several studies on the effects of real flight variations on noise. First, a study of longitudinal and vertical accelerations through the lens of flight path angle were conducted for the Sikorsky S-76D helicopter to understand how flight path angle and flight path angle rate changes can effect noise. Then, a study of helicopter configuration and the impact of weight and number of blades on noise was conducted. Four vehicles, the Sikorsky S-76D, the Bell 205, the Bell 407, and the Bell 206 were all analyzed in descent to understand how vehicle configuration influences noise.
