This paper uses a combined sensor array method to decompose ducted broadband noise into mode terms and to measure sound power within turbomachinery. The novelty of this method is that the number of required sensors is drastically reduced in comparison with current standard techniques, and only an axial line of microphones and one circular sensor ring are required. This superiority is more obvious in measurement of ducted broadband noise at medium and high frequencies. A numerical investigation on the accuracy and validity of this method is presented, including validating the accuracy experimentally for the first time. The synthetic sound fields in the numerical study are generated by several rings of uncorrelated monopole sources. Numerical results show that the characteristics of mode coherence coefficients are strongly dependent on the number of monopole sources and also the compactness of source distribution. The method is shown to be able to predict the incident broadband sound power with deviation less than 3 dB when mode waves are almost mutually uncorrelated. The fan ducted sound power calculated by this method is excellently consistent with that of current standard techniques. The deviation is less than 1 dB in the determination of incident sound waves, and increases to 3 dB in the reflected direction.
XU Kunbo
,
QIAO Weiyang
,
CHANG Xinyue
,
YIN Tao
,
HUO Shiyu
. Fan broadband noise based on combined sensor array method[J]. ACTA AERONAUTICAET ASTRONAUTICA SINICA, 2017
, 38(12)
: 121324
-121324
.
DOI: 10.7527/S1000-6893.2017.121324
[1] BOLLETER U, CROCKER M J. Theory and measurement of modal spectra in hard-walled cylindrical ducts[J]. The Journal of the Acoustical Society of America, 1972, 51(5):1439-1447.[2] MOORE C J. Measurement of radial and circumferential modes in annular and circular ducts[J]. Journal of Sound and Vibration, 1979, 62(2):235-256.[3] MORFEY C. Sound transmission and generation in ducts with flow[J]. Journal of Sound and Vibration, 1971, 14(1):37-55.[4] MUNJAL M L. Acoustics of ducts and mufflers[M]. New York:John Wiley & Sons, 1987:1-12.[5] 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, 2010:1-8. QIAO W Y. Aero-engine aeroacoustics[M]. Beijing:Beihang University Press, 2010:1-8(in Chinese).[6] MICHALKE A. On the propagation of sound generated in a pipe of circular cross-section with uniform mean flow[J]. Journal of Sound and Vibration, 1989, 134(2):203-234.[7] MICHALKE A. On experimental sound power determination in a circular pipe with uniform mean flow[J]. Journal of Sound and Vibration, 1990,142(2):311-341.[8] CHUNG J Y. Rejection of flow noise using a coherence function method[J]. The Journal of the Acoustical Society of America, 1977, 62(2):388-395.[9] ABOM M. Modal decomposition in ducts based on transfer function measurements between microphone pairs[J]. Journal of Sound and Vibration, 1989, 135(1):95-114.[10] ENGHARDT L, LOWIS C, NEUHAUS L. Broadband sound power determination in flow ducts:AIAA-2004-2940[R]. Reston, VA:AIAA, 2004.[11] JVRGENS W, TAPKEN U, PARDOWITZ B, et al. Technique to analyze characteristics of turbomachinery broadband noise sources:AIAA-2010-3979[R]. Reston,VA:AIAA, 2010.[12] JVRGENS W, PARDOWITZ B, ENGHARDT L, et al. Separation of broadband noise sources in aeroengine ducts with respect to modal decomposition:AIAA-2011-2879[R]. Reston, VA:AIAA, 2011.[13] LOWIS C R, JPSEPH P F, KEMPTON A J. Estimation of the far-field directivity of broadband aeroengine fan noise using an in-duct axial microphone array[J]. Journal of Sound and Vibration, 2010, 329(19):3940-3957.[14] GANZ U W, JOPPA P D, PATTEN T J, et al. Boeing 18-inch fan rig broadband noise test:NASA/CR-1998-208704[R].Washington, D.C.:NASA, 1998.[15] TAPKEN U, RAITOR T, ENGHARDT L. Tonal noise radiation from an UHBR fan-optimized in-duct radial mode analysis:AIAA-2009-3288[R]. Reston, VA:AIAA, 2009.[16] TAPKEN U, GUTSCHE D, ENGHARDT L. Radial mode analysis of broadband noise in flow ducts using a combined axial and azimuthal sensor array:AIAA-2014-3318[R]. Reston, VA:AIAA, 2014.[17] 许坤波, 乔渭阳, 王良峰, 等. 轴流风扇宽频噪声声功率实验研究[J]. 航空学报, 2015, 36(9):2939-2946. XU K B, QIAO W Y, WANG L F, et al. Experimental research of broadband sound power determination in axial fan[J]. Acta Aeronautica et Astronautica Sinica, 2015, 36(9):2939-2946(in Chinese).[18] MEYER H D, ENVIA E. Aeroacoustic analysis of turbofan noise generation:NASA-CR-1996-4715[R]. Washington, D.C.:NASA, 1996.[19] ENGHARDT L, HOLEWA A, TAPKEN U. Comparison of different analysis techniques to decompose a broadband ducted sound field in its mode constituents:AIAA-2007-3520[R]. Reston, VA:AIAA, 2007.[20] TAPKEN U, ENGHARDT L. Optimization of sensor arrays for radial mode analysis in flow ducts:AIAA-2006-2638[R]. Reston, VA:AIAA, 2006.[21] GOLDSTEIN M. Aeroacoustics[M]. New York:McGraw-Hill, 1976:57-69.[22] MICHALKE A, ARNOLD F, HOLSTE F. On the coherence of the sound field in a circular duct with uniform mean flow[J]. Journal of Sound and Vibration, 1996, 190(2):261-271.[23] TESTER B J, SIJTSMA P, JOSEPH P, et al. Fan broadband noise simulation:AIAA-2006-2684[R]. Reston,VA:AIAA, 2006.[24] JEONG W, JOSEPH P, LEE S. A wall-mounted source array for the excitation of incoherent broadband sound fields with prescribed modal distributions in ducts[J]. Journal of Sound and Vibration, 2006, 290(1):490-499.
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