Aircraft noise

About: Aircraft noise is a research topic. Over the lifetime, 3051 publications have been published within this topic receiving 32039 citations.

The validation and application of a rotor acoustic prediction computer program

Abstract: An essential prerequisite to reducing the acoustic detectability of military rotorcraft is a better understanding of main rotor noise which is the major contributor to the overall noise A simple, yet accurate, Rotor Acoustic Prediction Program (RAPP) was developed to advance the understanding of main rotor noise This prediction program uses the Ffowcs Williams and Hawkings (FW-H) equation The particular form of the FW-H equation used is well suited for the coupling of the measured blade surface pressure to the prediction of acoustic pressure The FW-H equation is an inhomogeneous wave equation that is valid in all space and governs acoustic pressure generated by thin moving bodies The nonhomogeneous terms describe mass displacement due to surface motion and forces due to local surface stresses, such as viscous stress and pressure distribution on the surface This paper examines two of the four types of main rotor noise: BVI noise and low-frequency noise Blade-vortex interaction noise occurs when a tip vortex, previously shed by a rotor blade, passes close enough to a rotor blade to cause large variations in the blade surface pressures This event is most disturbing when it happens on the advancing side of the rotor disk Low-frequency noise includes hover and low to moderate speed forward flight For these flight conditions, the low frequency components of the acoustic signal dominate

Cruise noise of the 2/9 scale model of the Large-scale Advanced Propfan (LAP) propeller, SR-7A

Abstract: Noise data on the Large-scale Advanced Propfan (LAP) propeller model SR-7A were taken in the NASA Lewis Research Center 8 x 6 foot Wind Tunnel. The maximum blade passing tone noise first rises with increasing helical tip Mach number to a peak level, then remains the same or decreases from its peak level when going to higher helical tip Mach numbers. This trend was observed for operation at both constant advance ratio and approximately equal thrust. This noise reduction or, leveling out at high helical tip Mach numbers, points to the use of higher propeller tip speeds as a possible method to limit airplane cabin noise while maintaining high flight speed and efficiency. Projections of the tunnel model data are made to the full scale LAP propeller mounted on the test bed aircraft and compared with predictions. The prediction method is found to be somewhat conservative in that it slightly overpredicts the projected model data at the peak.

Assessing aircraft noise-induced annoyance around a major German airport and its predictors via telephone survey – The COSMA study

Abstract: Background Despite technological improvements and noise mitigation schemes, annoyance due to aircraft noise remains an ongoing issue for residents near airports, and increasing annoyance has been observed in many affected communities. Objectives This study investigates aircraft noise-induced annoyance near a German airport that is particularly busy at night. In addition to established predictors, it examines variables not considered in studies of recent years. Annoyance ratings are compared to the current European standard exposure-response curve and the community tolerance level (Lct) is calculated as described in the 2016 revision of ISO 1996-1. Methods A telephone survey was conducted with 1262 residents near Cologne/Bonn Airport (IATA: CGN, Germany) which can be classified as a low-rate change (LRC) airport. Acoustical (Ldn in 5 dB-steps, flight altitude , and predominant type of operation) and non-acoustical variables (e.g., attitudes, noise sensitivity, urbanisation level of area) were recorded for every participant. Respondents assessed their aircraft noise-induced overall annoyance as well as their night-time annoyance using the verbal 5-point ICBEN scale. Results The Ldn explained 16.5% of variance in the annoyance ratings. The inclusion of non-acoustical variables into the regression model increased the proportion of explained variance to 54.8%. Annoyance prevalence rates at CGN were higher than predicted by the EU-standard curve and the Lct was lower than predicted by recent work. Conclusion For a LRC airport, the community around CGN shows an uncommonly high percentage of highly annoyed residents and a low tolerance to aircraft noise exposure. Non-acoustical factors including personal and situational factors seem to have substantial impact on annoyance.