Rotorcraft Noise Abatement Procedures Development PDF Download
Are you looking for read ebook online? Search for your book and save it on your Kindle device, PC, phones or tablets. Download Rotorcraft Noise Abatement Procedures Development PDF full book. Access full book title Rotorcraft Noise Abatement Procedures Development by Willca Villafana. Download full books in PDF and EPUB format.
Author: Willca Villafana Publisher: ISBN: Category : Languages : en Pages :
Book Description
A rotorcraft noise prediction system has recently been developed as part of aproject to develop and evaluate helicopter noise abatement procedures for a rangeof aircraft. The aim of this thesis is to demonstrate the noise prediction systemcapabilities and then consider simple noise abatement procedures for three differenthelicopters of varying technology levels and maximum gross weights.First, the codes that have been assembled into the noise prediction system aredescribed. A brief presentation of acoustic theory on which the noise prediction isbased is given as a reminder. Then, the noise prediction system has been validatedwith the Bell 430 helicopter flying in a level forward flight. The prediction systemhas also demonstrated its capacity to predict blade vortex interaction (BVI) noiseand BVI noise reduction. Finally several abatement procedures have been examined.The two first ones underscored the benefits of flying higher and slower by usingthe S-76C+ as an example. Then, a S-76C+, Bell 430 and BK 117 helicopterswere compared in a level forward flight. The comparison ended up with surprisingresults about loading and broadband noise since they do not appear correlated tothe weight of the rotorcrafts. Yet, thickness noise results are expected since theyare related to the rotor tip speeds. Finally, the effects of descent angle and speedon BVI noise have been demonstrated during approach. A Bell 430 helicopter wasused for this study and the speed and angle of descent were varied separately whilekeeping all the other parameters constant.
Author: Willca Villafana Publisher: ISBN: Category : Languages : en Pages :
Book Description
A rotorcraft noise prediction system has recently been developed as part of aproject to develop and evaluate helicopter noise abatement procedures for a rangeof aircraft. The aim of this thesis is to demonstrate the noise prediction systemcapabilities and then consider simple noise abatement procedures for three differenthelicopters of varying technology levels and maximum gross weights.First, the codes that have been assembled into the noise prediction system aredescribed. A brief presentation of acoustic theory on which the noise prediction isbased is given as a reminder. Then, the noise prediction system has been validatedwith the Bell 430 helicopter flying in a level forward flight. The prediction systemhas also demonstrated its capacity to predict blade vortex interaction (BVI) noiseand BVI noise reduction. Finally several abatement procedures have been examined.The two first ones underscored the benefits of flying higher and slower by usingthe S-76C+ as an example. Then, a S-76C+, Bell 430 and BK 117 helicopterswere compared in a level forward flight. The comparison ended up with surprisingresults about loading and broadband noise since they do not appear correlated tothe weight of the rotorcrafts. Yet, thickness noise results are expected since theyare related to the rotor tip speeds. Finally, the effects of descent angle and speedon BVI noise have been demonstrated during approach. A Bell 430 helicopter wasused for this study and the speed and angle of descent were varied separately whilekeeping all the other parameters constant.
Author: Mrunali Botre Publisher: ISBN: Category : Languages : en Pages :
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: New Jersey. Legislature. General Assembly. Airport Noise Abatement Study Committee Publisher: ISBN: Category : Airport noise Languages : en Pages : 48
Author: Willca Villafana
Author: Willca Villafana
Author: Interagency Aircraft Noise Research Panel
Author: Mrunali Botre
Author: United States. Federal Aviation Administration. Office of the Secretary
Author: William C. Sperry
Author: 
Author: International Civil Aviation Organization
Author: New Jersey. Legislature. General Assembly. Airport Noise Abatement Study Committee
Author: United States. Office of Noise Abatement
Author: United States. Office of Noise Abatement