Aircraft noise

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

Prediction methods for Near Field Noise Environments of VTOL Aircraft.

Abstract: : This report establishes a consistent set of prediction methods which may be used to estimate near field noise levels for jet powered and rotor/propeller powered VTOL aircraft operating in close proximity to the ground. The methods provided utilize available theory augmented extensively by experimental data which was available or was obtained during the program. The noise prediction methods presented will allow an analysis of near field environments of VTOL aircraft using a simplified procedure suitable for manual calculations. The experimental effort carried out in the program consisted of noise measurements in the near field of a model propeller and a subsonic jet in a free and vertical configuration. Ground reflection correction factors for a simple source are tabulated along with the computer program listing. The methods described in this report are intended for use by aircraft designers for the prediction of the near field noise environment of VTOL aircraft as required in MIL A 8893 Airplane Strength and Rigidity, Sonic Fatigue Resistance.

Airport noise simulation using neural networks

Abstract: Aircraft noise is influenced by many complex factors and it is difficult to devise an accurate mathematical model to simulate it with respect to operations at an airport. This paper presents an investigation in simulating airport noise using artificial neural networks. The results show that it is possible to establish a simple neural network model with monitored data for a specific airport and specific aircraft under local conditions.

Validation of DLR's sound shielding prediction tool using a novel sound source

Abstract: This paper is concerned with an experimental validation methodology for DLR’s acoustic shielding prediction boundary element code BEMPAR. This code in turn will be integrated into the overall aircraft noise prediction tool PANAM of DLR. The presented validation concept is based on a novel laser-based sound source. Almost perfect monopole-type test signals may be produced with a frequency content up to roughly 100kHz in combination with a very small source extension. These characteristics make this technique especially attractive for shielding/installation tests, which typically have to be performed at relativey small scale. BEMPAR is a boundary element code (BEM) which solves for the scattered pressure field. Three generic test cases are evaluated, a circular plate, a long cylinder and DLR’s low noise aircraft (LNA-1) nacelle model. The outcome of this investigation clearly demonstrate the potential of BEMPAR for the prediction of installation eects.

Empirical prediction of flap tip noise.

Abstract: In this paper, DLR’s empirical prediction model for flap tip noise is presented and discussed in details. The prediction scheme is based on a comprehensive acoustic and aerodynamic database acquired in the Acoustic Wind Tunnel Braunschweig. It was verified, through successful scaling of the measured noise spectra, that the cross-flow velocity at the flap tip is an important parameter characterizing the flow mechanism(s) responsible for the noise production. This finding led to the definition of a universal flap tip noise spectral shape in terms of a linear least-squares fit of the corresponding measurement data. Using a similar approach, a model for the flap tip noise directivity was formulated. The prediction model was compared against full-scale fly-over measurement data (B747-400 and A319) and an acceptable agreement of the overall predictions was found. A slight underprediction of the noise levels at high frequencies suggests that additional airframe noise sources might be needed in the complete aircraft noise prediction scheme to get a better agreement between measured and predicted noise levels. It is also found that, for large flap deflection angles, flap tip noise dominates the high frequency part of the predicted complete aircraft high-lift noise spectra. Knowledge of the flap tip noise peak frequency and high-frequency decay are therefore sufficient to account for this noise source in the total aircraft noise prediction. Finally, the limitations of the prediction scheme are discussed and research needs are identified.