Российский фонд
фундаментальных
исследований

Физический факультет
МГУ им. М.В.Ломоносова
 

X

Xiaodong Li

 

Xiaodong Li, Baohong Bai «Influence of low noise design of large commercial aircraft airframe on certification noise» Тезисы докладов Шестой открытой Всероссийской (XVIII научно-технической) конференции по аэроакустике (22–27 сентября 2019 г.), с. 80-82 (2019)

Considerable efforts have been made to attenuate airframe noise. Several passive and active flow-control techniques have been proposed to reduce the slat low-frequency noise, which is the most prominent component in slat noise spectra in real aircraft Slat cove cover and slat cove filler [Imamura T., Ura H., Yokokawa Y., Enomoto S., and Yamamoto K. “Designing of Slat Cove Filler as a Noise Reduction Device for Leading-Edge Slat,” 13th AIAA/CEAS Aeroacoustics Conference, AIAA Paper 2007-3473] modifications that postpone or eliminate shear layer formation provide significant acoustic benefits. In the case of the cove filler, the broadband noise is reduced by 3–4 dB. However, it is difficult for the slat with cove cover or slat cove filler to retract and form a seamless surface when the slat is not desirable. Alternatively, a blade seal [Khorrami M.R., and Lockard D.P. “Effects of Geometric Detail on Slat Noise Generation and Propagation, International Journal of Aeroacoustics. 2010. Vol. 9, No. 4-5. Pp. 655-678] gives a 2–3 dB reduction at low frequencies (less than 2 kHz), whereas an elongated blade seal eliminates most of the small-scale vortices generated at the cusp. The application of acoustic liner treatments [Ma Z., and Zhang X. “Numerical Investigation of Broadband Slat Noise Attenuation with Acoustic Liner Treatment,” AIAA Journal. 2009. Vol. 47. No. 12. Pp. 2812-2820] can also be used to attenuate the noise. Kopiev et al. [Kopiev V.F., Zaitsev M.Y. and Belyaev I. . “Noise Reduction Potential Through Slat Hook Serrations,” 17th AIAA/CEAS Aeroacoustics Conference, AIAA Paper 2011-2909] suppressed narrowband peaks located in the frequency region 1.5-7 kHz by serrated slat hooks. Kuo and Sarigul-Klijn [Kuo В. C. and Sarigul-Klijn N. “Conceptual Study of Micro-Tab Device in Airframe Noise Reduction: (2) 3D Computation," Aerospace Science and Technology.2012. Vol. 17. No. 1. Pp. 32-39] reduced the deployment angle of the slat to suppress the slat noise, which increases rapidly if the deflected angle of the slat is enlarged. The loss of lift efficiency was compensated by a micro tab implemented at the flap pressure side. Wild et al. 6 attenuated the slat noise by implementing the very long slat chord to lower the speed of the slat trailing-edge flow. However, these noise suppression techniques are far from being applied into the real aircraft, because high-lift devices must satisfy the aerodynamic requirement firstly. An aerodynamic and aeroacoustics optimization design method for high-lift device was established by the authors recently [Wild J., Pott-Pollenske M., Nagel B. “An Integrated Design Approach for Low Noise Exposing High-Lift Devices," AIAA Paper 2006-2843]. The optimization design method integrated the parameterized geometric model, mesh generation, CFD computation and far field noise prediction technique. The optimization design based on a genetic algorithm (GA) was accomplished for multi-element airfoil. The 30P30N three-element high-lift airfoil was selected as the baseline airfoil and optimized in aerodynamic and aeroacoustics. The location and orientation parameters of the slat relative to the main wing, defined by deflection angle, overlap and gap, were optimized to obtain the maximum lift coefficient, which can be calculated by CFD and minimum radiated noise level. The physics-based slat noise model proposed by Guo 68, 99 was applied to predict the high-lift far field noise level. The optimized three-element airfoil was proved to have a better aerodynamic performance and the minimum of the noise level was obtained. In the present paper, the aerodynamic and aeroacoustics optimization design of high-lift device at landing condition will be given. Meanwhile, the gains of airframe noise reduction on certification noise will be evaluated. An airframe noise prediction method based on physics was developed, which can reflect the impact of the low noise airframe configuration and flight path on certification noise. The aircraft certification noise is predicted and the airframe noise contour map is plotted for a particular aircraft. The method can provide a reference for the low noise design of airframe configuration and flight path.

Тезисы докладов Шестой открытой Всероссийской (XVIII научно-технической) конференции по аэроакустике (22–27 сентября 2019 г.), с. 80-82 (2019) | Рубрика: 10.06

Xingqiang Liu

 

Xingqiang Liu, Wenchao Huang, Hao Yan, Hongli Li «Tandem cylinder noise characteristics research and advance noise reduction method exploration» Тезисы докладов Шестой открытой Всероссийской (XVIII научно-технической) конференции по аэроакустике (22–27 сентября 2019 г.), с. 203-206 (2019)

With the reduction of jet noise associated with high pass ration engines on large civil transport aircraft. The airframe noise has become a primary noise source during takeoff and landing. A major component of airframe noise is the deployed landing gear. The configuration of landing is very complex; noise originates from the flow separation due to complex buff bodies and the wake flow multiple interactions with downstream components. Tandem cylinder represents generic flow geometry relevant to landing gear. The major interest is the nature of interaction of unsteady wake from upstream cylinder with the downstream cylinder. Wake interactions are expected to have a big impact on the noise generation. Experiment has been performed in this paper to access the noise characteristics, basing on the mechanism of noise generation, some advance control methods, such as plasma and turbulence, were used to reduce the noise.

Тезисы докладов Шестой открытой Всероссийской (XVIII научно-технической) конференции по аэроакустике (22–27 сентября 2019 г.), с. 203-206 (2019) | Рубрика: 04.11