微穿孔板结构吸声性能的提升

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1、微穿孔板结构吸声性能的提升效果，复合共鸣器的机械阻抗板只需要很小的空间距离就能有效吸收低频声能量，选择三角孔微穿孔板和复合共鸣器的机械阻抗板来提高微穿孔板结构的吸声性能，在技术上有进步意义，更具有实际应用价值。关键词：噪声控制，微穿孔板，机械阻抗，声阻抗，赫姆霍兹共鸣器，阻抗转移Ⅱ江苏大学硕士学位论文ABSTRACTThetraditionalmicro—perforatedpanelfMVa)absorberiscomposedofmicro-poreandcavity,andreducesnoisebycavityresonance．Relativeresistanceofthew

2、holestructureCallbecontrolledbytheacousticresistanceofmicro-pore，andthereisnoneedtofillanysound—absorbingmaterialinthebackcavity．Itsimplifiessound-absorbingstructure，andavoidssecondarypollutiontotheenvironment．Asaconsequence，itissuitableforhighcleanlinessandhighsoundintensityrequirements．Inthisp

3、aper,howtoimprovethesoundabsorptionperformanceofMPPstructureWaSstudied．TriangleporeMPPwasusedtoimprovesoundabsorptionofMPPinmedium-highfrequency．ThetriangleporeMPPisanewstructureofMPETheacousticimpedanceoftriangleporeMPPwasmeasuredbytest．Then,thesoundabsorptioncharacteristicsoftriangle—poreMPPwe

4、reanalyzedandcomparedwiththetraditionalMPPwiththesameperforationrate．Absorptioncoefficientofdouble—layertriangleporeMPPwascalculatedbymeasuredacousticimpedance，andtheresultwascomparedwiththatoftestanddouble—layerroundporeMPP．Thepromotionmechanismofsoundabsorptionperformancewasanalyzed．Mechanical

5、impedanceunitwasintroducedintotraditionalMPPstructuretoabsorbnoiseinlowfrequency．ThenewcombinedstructureiscomposedofMIPandMPEEachsoundabsorptionunitofthecombinedstructurewasanalyzed．Theabsorptionformulaoftheproposedcombinedstructurewasderivedbyimpedancetransfermethod．Thedampingandstiffnesscoeffi

6、cientsoftheMIPweredeterminedbythehalf-powerbandwidthmethod．Thesoundabsorptioncoefficientcurveofthecompositestructurewasmeasuredbystandingwavetubeexperimentandtheresultswerecomparedwiththecalculativesoundabsorptioncoefficient．HRwasintroducedtoabsorbnoiseinlowfrequency．HRisfixedontheMIPtocompensat

7、ethesoundabsorptionperformancebetweenmechanicalimpedanceresonanceandMPPresonance．Theabsorptionformulaoftheproposedcombinedstructurewasderivedbyimpedancetransfermethod，andcorrespondingtestsweredonetoverifytheabsorptionformula