作为风扇出口导向叶片（Outlet Guide Vanes，OGV）低噪声设计系列文章的第2篇，本文对气动/声学一体化设计获得的2个OGV低噪声方案的降噪效果进行了数值验证。为了对低噪声优化方案的降噪效果进行详细评估，首先，采用非线性谐波法对优化前后的风扇/增压级开展了数值仿真，对OGV不同截面和叶片表面脉动压力进行了对比分析，发现低噪声优化设计方案有效降低了转/静干涉引起的脉动压力；然后，通过掠形和倾斜的合理组合，改变了叶片表面的相位分布，沿径向的相位变化增加了OGV对尾迹响应相互抵消的机会，从而有利于噪声的降低；最后，采用Wilson的波分解方法开展了对各方案的模态分析，对降噪效果进行了量化评估。结果显示，优化后的低噪声方案除起飞状态1BPF外，降噪量均超过了5 dB。
As the second part of the ‘Low noise design of fan outlet guide vane’ serial articles, this paper numerically evaluates the rotor/stator interaction noise of the two swept and leaned Outlet Guide Vanes (OGVs) obtained in the first paper and explored the noise reduction mechanism. First, a non-linear harmonic method is adopted to simulate the fan stage with different OGVs. The perturbation pressure on several sections and blade surface of OGV is investigated and analyzed. It is found that the perturbation pressure amplitudes of the low-noise design OGVs and the interaction noise are significantly reduced. Then, the optimized combination of sweep and lean resulted in a different distribution of phase on the blade surface. The radical variation of phase enhances the cancelation of the response of OGV to the rotor wake, being conducive of noise reduction. Finally, Wilson's wave splitting method is employed to quantitatively evaluate the sound power levels. The results show that, the rotor/stator interaction noise is reduced dramatically due to the low noise design, and a minimum of 5 dB of noise reduction can be obtained at different power sets except at take off for the 1st BPF.
[1] 乔渭阳. 航空发动机气动声学[M]. 北京:北京航空航天大学出版社, 2010:168-171. QIAO W Y. Aeroacoustic of aeroengines[M]. Beijing:Beihang University Press, 2010:168-171(in Chinese).
[2] LIGHTHILL M J. On sound generated aerodynamically. II Turbulence as a source of sound[J]. Proceeding of the Royal Society of London, Series A, 1952, 211(1107):564-587.
[3] CUMPSTY N A. A critical review of turbomachinery noise[J]. ASME Journal of Fluids Engineering, 1977, 99:278-293.
[4] 孙晓峰, 周盛. 气动声学[M]. 北京:国防工业出版社, 1993:94-95. SUN X F, ZHOU S. Aeroacoustics[M]. Beijing:National Defense Industry Press, 1993:94-95(in Chinese).
[5] 蒋永松, 郑文涛, 赵航, 等. 风扇出口导向叶片低噪声设计I:方法与优化[J]. 航空学报,2019,40(10):122955. JIANG Y S, ZHENG W T, ZHAO H, et al. Low noise design of high bypass ratio fan outlet guide vanes,part I:Method and optimization[J]. Acta Aeronautica et Astronautica Sinica,2019,40(10):122955(in Chinese).
[6] WOODWARD R P, ELLIOTT D M, HUGHES C E, et al. Benefit of swept-and-leaned stators for fan noise reduction[J]. Journal of Aircraft, 2001, 28(6):1130-1138.
[7] KAZIN S B. Radially leaned outlet guide vanes for fan source noise reduction:CR-134486[R]. Washington,D.C.:NASA, 1973.
[8] ENVIA E, NALLASAMY M. Design selection and analysis of a swept and leaned stator concept[J]. Journal of Sound and Vibration,1999, 228(4):793-836.
[9] 张伟光, 王晓宇, 孙晓峰. 叶片弯掠组合设计对风扇气动噪声的被动控制[J]. 航空学报,2017,38(2):120265. ZHANG W G, WANG X Y, SUN X F. Passive control of fan noise by vane sweep and lean[J]. Acta Aeronautica et Astronautica Sinica, 2017, 38(2):120265(in Chinese).
[10] NAMBA M. Three-dimensional analysis of blade force and sound generation for an annular cascade in distorted flows[J]. Journal of Sound and Vibration, 1977, 50(4):479-508.
[11] 王晓宇. 传递单元方法及其在航空发动机短舱声学问题中的应用[D]. 北京:北京航空航天大学, 2009:66-90. WANG X Y, Transfer element method and its application in the acoustic design of aeroengine[D]. Beijing:Beihang University, 2009:66-90(in Chinese).
[12] MEYER H D, ENVIA E. Aeroacoustic analysis of turbofan noise generation:CR-4715[R]. Wshington,D.C.:NASA, 1996.
[13] MAJJIGI R K,GLIEBE P R. Development of a rotor wake/vortex model,Volume I:Final report:CR-174849,[R]. Wshington,D.C.:NASA, 1984.
[14] HE L, NING W. Efficient approach for analysis of unsteady viscous flows in turbomachines[J]. AIAA Journal, 1998, 36(11):2005-2012.
[15] VILMIN S, LORRAIN E, HIRSCH C. Unsteady flow model across the rotor/stator interface using the nonlinear harmonic method:GT2006-90210[R]. New York:ASME,2006.
[16] WILSON A G. A method for deriving tone noise information from CFD calculations on the aeroengine fan Stage[C]//NATO RTO-AVT Symposium on Developments in Computational Aero-and Hydro-Acoustics, 2001.
[17] GIACCHÉ D, XU L, COUPLAND J, et al. A comparison between postprocessing methods applied to rotor-stator-interaction tone-noise problems[J]. AIAA Journal, 2011, 49(6):1214-1229.
[18] NUMECA International. FINETM/Turbo 11.2-User Guide[M].Brussels:NUMECA International:12-17.
[19] ENVIA E, NALLASAMY M. Design selection and analysis of a swept and leaned stator concept[J]. Journal of Sound and Vibration, 1999, 228(4):793-836.
[20] TYLER J M, SOFRIN T G. Axial flow compressor noise studies[J]. SAE Trans, 1962, 70:309-332.
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