Aircraft noise

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

Folded cavity liners for turbofan engine intakes

Abstract: Reducing aircraft noise is crucial to the growth of air transport and quality of people’s lives. Fan noise propagates through engine intake and bypass ducts and is radiated to the far eld. It is a major contributor to aircraft noise at take-o and landing. Acoustic liners are installed on the internal walls in the engine ducts to attenuate the fan noise. They are typically single or double degree of freedom liners, and their acoustic performance is strongly dependent on the cell depth. Typical cell depths are selected to attenuate noise in the frequency range which is critical to community noise. Increasing the attenuation at low frequencies requires deeper cells, which is often prohibited by mechanical design constraints. A potential remedy would be to fold the cells to t in a shallow space. In this study, the design and performance of folded cavity liners for turbofan engine intakes are investigated. A nite element model was developed for predicting acoustic impedance of such liners. The numerical model was used for parametric studies and validated against test data. The acoustic performance of folded cavity liners when installed in the nacelle of a rig intake was predicted by using a nite/innite element analysis with the predicted acoustic impedance of a folded cavity liner and compared to the noise reduction by an optimised community noise liner. It is demonstrated that folded cavity liners work as a combination of a deep and shallow liners corresponding to the centreline length and the hight to the fold. The performance can be tuned and optimised to be eective over wide frequency range by selecting the geometry and properties of resistive layers, i.e., facing and septum sheets. Folded cavity liners have a great potential to provide a solution for reducing both mid-high frequency community noise as well as low-frequency noise.

A multilevel optimization approach to route design and flight allocation taking aircraft sequence and separation constraints into account

Abstract: This paper presents the development of a multilevel optimization framework for the design and selection of departure routes, and the distribution of aircraft movements among these routes, while taking the sequence and separation requirements for aircraft on runways and along selected routes into account The main aim of the framework is to minimize aircraft noise impact on communities around an airport, and the associated fuel consumption The proposed framework features two consecutive steps In the first step, for each given Standard Instrument Departure (SID), multi-objective trajectory optimization is utilized to generate a comprehensive set of possible alternative routes The obtained set is subsequently used as input for the optimization problem in the second step In this step, the selection of routes for each SID and the distribution of aircraft movements among these routes are optimized simultaneously To ensure the feasibility of optimized solutions for an entire operational day, the sequence and separation requirements for aircraft on runways and along selected routes are included in this second phase In order to address these issues, three novel techniques are developed and added to a previously developed multilevel optimization framework, viz, a runway assignment model, a conflict detection algorithm, and a rerouting technique The proposed framework is applied to a realistic case study at Amsterdam Airport Schiphol in the Netherlands, in which 599 departure flights and 13 different SIDs are considered The optimization results show that the proposed model can offer conflict-free solutions, one of which can lead to a reduction in the number of people annoyed of up to 21%, and a reduction in fuel consumption of 8% relative to the reference case solution

Jet noise at schools near Los Angeles International Airport.

Abstract: In this study, indoor and outdoor measurements of jet aircraft noise were made at seven schools beneath the eastern approach paths to the Los Angeles International Airport. At five elementary schools, the jet noise in the schoolyards ranged from 96 to 118 dBC and constituted a high risk of hearing damage for the children. The frequency of jet aircraft overflights averages one per 2‐min interval for a total of about 200 per school day (8:30 a.m.–3:30 p.m.). The corresponding jet‐noise levels in the classrooms (80% of which are not air‐conditioned or acoustically treated) ranged from 80 to 96 dBA and caused continual disruption of communication and the learning processes. An investigation of aircraft operation alternatives indicated that the noise could be reduced by 10 dB or more if engine power were properly managed when the aircraft approaches the school areas, or if the aircraft approached at higher altitudes and landed further to the west on the unused 6000‐ft‐long portion of the 12 000‐ft‐long runways.

Noise considerations for tiltrotor

Abstract: A projection is made of the technology-development requirements faced by aircraft designers contemplating the evolution of V-22-type tilt-rotor aircraft technology into a civilian tilt-rotor commuter aircraft of the requisite scale and payload. These research challenges are noted to often involve the reduction of noise level to values tolerated by passengers within the cabin and communities in the vicinity of airports, especially during hover and in the course of transition from vertical to horizontal flight (and vice-versa). Noise-generation and noise-radiation characteristics research has been undertaken using the XV-15 tilt-rotor proof-of-concept aircraft.

Aircraft Noise Identification System By Correlation Technique

Abstract: The growth of environmental noise by traffic, construction, or manufacturing bring increasing interference in listening to television and radio, as well as in other human activities. The Japanese government's national -projects for noise abatement are making progress in the revision of land-use compatibility and sound-proofing of dwellings. Through the Broadcasting Act, the Japan Broadcasting Corporation (NHK) has made a discount of the TV receiver's fee for compensation of interence in listening to TV by aircraft noise within restricted areas around airports and airbases.