Search

Aerodynamic and aeroacoustic experiments of 30P30N three-element high-lift configuration are conducted in D5 aeroacoustic wind tunnel at Beihang University. The test section is composed of Kevlar and perforated plate which can measure aerodynamic features with less jet shear layer interference and aeroacoustic characteristics with good sound transmission simultaneously. Aiming at the research of high-lift configurations during the aircraft approach and landing, Mach number and angle of attack vary from 0.09 to 0.17 and 3 ° to 8 ° , respectively. The measured surface pressure distributions in D5 agree well with the results of JAXA-LWT2 and computational fluid dynamics predictions. Consistent with previous investigations, the far-field noise spectra obtained by 1/2 in. free-field microphones nearly decrease with a slope proportional to f - 2 in a wide frequency range and scale with Ma 4.5 . Moreover, all mid-frequency peaks are observed in the range of 1 < St < 5 with one maximum within St = 1 - 3 . The tonal frequencies and noise spectral shape seem less sensitive to the tested angles of attack, except that the tonal intensity decreases with increasing angles of attack. Noise source maps for 1/3 octave band obtained from data processed by conventional beamforming with the far-field noise spectra indicate that the slat cove and slat-main element region is the main noise source that can radiate narrow-band peaks. [ABSTRACT FROM AUTHOR]

The D5 aeroacoustic wind tunnel at Beihang University is a newly commissioned small-scale closed-circuit wind tunnel with low turbulence intensity and low background noise. The wind tunnel is built to study both aerodynamic and aeroacoustic performance of aircraft components or scaled models. The wind tunnel has two types of test sections, the closed type test section is used for aerodynamic tests while the open type test section is mainly used for aeroacoustic experiments. Both types of test section are 1 m in height and 1 m in width, and the maximum wind velocity in the test section can be up to 80 m/s. An anechoic chamber is built surrounding the test section to provide the non-reflecting condition. This paper provides an overview of design criteria and performance of the small-scale wind tunnel. The layout of the wind tunnel and some critical design treatments to improve aerodynamic and acoustic performance are discussed in detail. Some experiments are conducted to verify the performance of D5 wind tunnel, results confirm that the turbulence intensity is less than 0.08% in the core of test section and the background noise is comparable with other aeroacoustic wind tunnels. A scaled simplified nose landing gear model is also measured as a benchmark test, results reveal that noise radiated from the model is adequately higher than the background noise for a wide frequency range and remarkably consistent with other results from literatures. [ABSTRACT FROM AUTHOR]