Airframe noise characteristics of a 1/11 scale Airbus model

Abstract

In the context of airframe noise research, ONERA performed tests on a 1:11 scale aircraft model in the CEPRA 19 anechoic wind tunnel. This paper provides an overview of the data acquired during these tests. The main purpose was to evaluate the relevance of scale model experiments for airframe noise study. The test program included acoustic source localization and far-field measurements. Various configurations were studied in order to isolate and compare the different noise sources. Each test was performed at flow velocities from 40 m/s up to 100 m/s in order to assess noise level and spectral shape variations with respect to the velocity. Landing gear (LG) and high-lift devices (HLD) appeared as the main contributors to airframe noise. These noise sources exhibit a Strouhal number dependence with level varying at the sixth (LG) and fifth (HLD) powers of flow velocity. A 2D crossshaped array was used to generate acoustic source maps with which we were able to locate some important sources on the slat and at the junctions between flap elements. Far-field / near-field correlations were successfully used to characterize noise sources on the instrumented inboard tab. Slot noise exhibited a spectral shape independent of the flow velocity. In contrast, flap side-edge noise showed a Strouhal number dependence. The far-field spectra were then projected to full scale flight conditions and compared to flight data. NOMENCLATURE