Determination of Absolute Contributions of Aircraft Noise Components Using Fly-over Array Measurements

作者：Pieter Sijtsma, Robert Stoker · 年份：2004 · DOI：10.2514/6.2004-2958 · 被引用次数：88 · 研究领域：Aerodynamics and Acoustics in Jet Flows、Acoustic Wave Phenomena Research、Noise Effects and Management

†For wind tunnel array measurements, the source power integration technique has proved to be a valuable technique to determine absolute source levels. This paper describes the extension of the source power integration technique to moving sources, and the application to fly-over array measurements on landing aircraft at Amsterdam Airport Schiphol. The technique is applied in combination with a modified version of the Delay-and-Sum beamforming technique, which includes microphone- and frequency-dependent weight factors. These weight factors are used to correct for microphone spatial density and to account for the effects of coherence loss. This beamforming technique works well in combination with the array design, which consists of a number of concentric rings of microphones, with increasing density towards the center. In this paper, it is demonstrated that the extended source power integration technique is able to determine absolute levels from fly-over array measurements, when it is used in combination with the special beamforming technique and the Schiphol array design. Thus, absolute quantification of difference source regions on an aircraft is feasible. Microphone auto-correlations must be included in the beamforming process in order to obtain correct integrated levels, although acoustic images look better when beamforming is done without auto-correlations. The source power integration technique is applied to a Boeing 737-400, and to an Airbus A340.