Bolton, J Stuart

Lee, Seungkyu

English

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Purdue UniversityPurdue e-PubsPublications of the Ray W. Herrick Laboratories School of Mechanical Engineering8-11-2015Design of an Acoustic Silencer withMicroperforated Elements Considering FlowEffectsJ Stuart BoltonPurdue University, bolton@purdue.eduSeungkyu Leesklee36@purdue.eduFollow this and additional works at: http://docs.lib.purdue.edu/herrickThis document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact epubs@purdue.edu foradditional information.Bolton, J Stuart and Lee, Seungkyu, "Design of an Acoustic Silencer with Microperforated Elements Considering Flow Effects"(2015). Publications of the Ray W. Herrick Laboratories. Paper 109.http://docs.lib.purdue.edu/herrick/109D e s i g n  o f  a n  a c o u s t i c  s i l e n c e r  w i t h  m i c r o p e r f o r a t e d e l e m e n t s  c o n s i d e r i n g  f l o w  e f f e c t sS E U N G K Y U L E E  A N D  J .  S T U A R T  B O L T O NR A Y  W .  H E R R I C K  L A B O R A T O R I E S ,  P U R D U E  U N I V E R S I T YI N T E R - N O I S E  1 5 ,  S A N  F R A N C I S C O ,  U S A8 / 1 1 / 2 0 1 5  T U E S D A YAcknowledgement2 3M Company, USA The authors acknowledge the support of 3M Corporation through the provision of materials for the fan noise experiments and for the financial support of this work.Previous work (Presented at Noise Con 2014)3 A cylindrical MPP lining has beneficial effects in reducing the minima in the transmission loss of an expansion muffler.0 500 1000 1500 2000 2500 3000 3500 4000 4500 50000102030405060Frequency [Hz]TL [dB]Transmission Loss of Single Muffler  Single Chamber FEMSingle Chamber EXPSingle w/ MPP454 FEMSingle w/ MPP454 EXP Dual chamber muffler with double-MPP lining showed flat TL curve of the muffler over the speech interference range.0 500 1000 1500 2000 2500 3000 3500 4000 4500 50000102030405060708090100Frequency [Hz]TL [dB]TL for Double layered MPP linings of Double Expansion Muffler  Double Chamber FEMDouble Chamber EXPDouble w/ MPP454 FEMDouble w/ MPP454 EXPDouble-layered MPP454 Linings FEMDouble-layered MPP454 Linings EXPPrevious work (Presented at Noise Con 2014)4 MPP linings in the muffler system were not only advantageous in reduction of minima in the transmission loss curve but also have beneficial effects in improvement of pressure drop.170 180 190 200 210 220 230 240 25002468101214161820Single Chamber Muffler Pressrue DropFlow Rate [STD LPM]Pressrue Drop [Pa]  Impermeable LiningMPP 549 LiningMPP 454 LiningMPP 273 LiningSingle Chamber Muffler No liningSingle chamber Muffler with a MPP lining2. Develop FE model of MPP with mean flow effectPresent Objective5 Develop an acoustic silencer that can attenuate sound efficiently over the speech interference range (400 – 4000 Hz) using Microperforated Panels (MPPs) and considering flow effects. Internal structural design: Inlet/outlet extensions, multiple chambersMuffler Design considering flow effect procedure1. TL Measurement of MPP liner• TL measurement of MPP liner considering flow effect using the standing wave tube. • Develop the FE model of MPP and validate with the measured TL3. Design muffler with validation• Create the FE prediction model of muffler and validate with the measured TLTransmission Loss measurement considering mean flow61 34 34 412 12 11 121 34 34 412 12 21 22,/  a aa a ap A B pA B T Tv C D p ZC D T T                        11 12 0 0 21 222/jkdaeTT T c cT T   10120logaTLT 4 – Microphone and 2 – load Method Transfer Matrix Calculation* Transmission Loss0cos sin( / )sin cosc c cjMk lc cz z lk l jY k lp pej Y k l k lv v              02( )1ck j MkM00 0( ) ( )1M MY Y jk k      * M. L. Munjal, Acoustics of Ducts and Mufflers, WILEY (2014)Microperforated Panel (MPP) Modeling7MPP modeling Equivalent fluid – JCA model 1,2 Complex Density and Bulk Modulus were modeled using following equations Calculated properties were implemented in the finite element model of the MPP Rigid inclusions to make the MPP locally reacting. *20 02 2 204( ) 1 1cs j j                 012020/( )'8( 1) 1 1' 16ppPKCj jC              1) Champoux Y. and Allard J.-F., Dynamic tortuosity and bulk modulus in air-saturated porous media, J. Appl. Phys. 70, 1991, pp. 1975-19792) L. Jaouen and F.-X. Be´cot, “Acoustical characterization of perforated facings”, J. Acoust. Soc. Am. 129 (3), March 2011* S. Lee, J. S. Bolton and P. A. Martinson, “Design of multi-chamber silencers with microperforated elements,” NoiseCon 14 Conference Proceedings, Fort Lauderdale, Florida, USA (2014)Complex Density : Complex Bulk Modulus : φ:  Perforation rateα:  Dynamic Tortuosityσ: Flow resistivityη: Dynamic viscosity of airΛ: Viscous characteristic lengthΛ‘:  Thermal characteristic lengthΛ = Λ ‘ = r (radius of perforation)k:  Thermal conductivity γ: Specific heat ratio of airPo:  Atmospheric pressureCp:  Specific heat of air at const. pressure MPP PropertiesMPP 549Hole diameter [μm] 126.6Thickness [mm] 0.35Flow resistance [Rayls] 549MPPFinite Element Model – Flow Effect8 Square cross-section standing wave tube model20 0201 1( ) ( )1( ) 0vv v vn vv n v  = VSjp I p p p p p pp dVc Kjp I p p dSc                            Variational form, Helmholtz EquationFlow velocity applied in red region Sound Pressure along the duct1 1jkx jkxM Mp Ae Be   Anechoic Termination2(1 ) nanechoicj iM p Mp pc Z        0anechoicZ cTL Results Comparison90 500 1000 1500 2000 25000123456789Frequency [Hz](a)TL [dB]  0 500 1000 1500 2000 25000123456789Frequency [Hz](b)TL [dB]  No MPP without mean flow (Measurement)No MPP with mean flow, 8.5 m/s (Measurement)No MPP without mean flow (Prediction)No MPP with mean flow, 8.5 m/s (Prediction)0 500 1000 1500 2000 25000123456789Frequency [Hz](a)TL [dB]  0 500 1000 1500 2000 25000123456789Frequency [Hz](b)TL [dB]  MPP549 without no flow fem (Prediction)MPP549 with mean flow, 8.5 m/s (Prediction)MPP 549 without mean flow (Measurement)MPP 549 with mean flow, 8.5 m/s (Measurement)Measurement PredictionMean FlowP1 P2 P3 P4No Mean FlowP1 P2 P3 P4 MPP lining attachedMean FlowP1 P2 P3 P4No Mean FlowP1 P2 P3 P4 No MPP liningFlow effects in the TL of the muffler 10 The prototype muffler used in this study  Muffler attached to the standing wave tube  Two end terminationsLoad 1 Load IIDimension [cm]lt 9.60do 15.2di 2.90 Flow velocity21.6 m/s, M = 0.063Comparison Results – Single chamber muffler11 Measurement VS PredictionMean FlowFlow VS  No Mean flow0 1000 2000 3000 4000 5000 600005101520253035404550Frequency [Hz]TL [dB]Transmission Coefficient  Single chamber, No lining, EXP, No flowSingle chamber, No lining, EXP, Flow velocity: 20m/s0 1000 2000 3000 4000 5000 600005101520253035404550Frequency [Hz]TL [dB]Transmission Coefficient  Single chamber, No lining, EXP, Flow velocity: 20m/sSingle chamber, No lining, FEM, Flow velocity: 20m/sMean Flow Measurement:Comparison Results – Single chamber muffler120 1000 2000 3000 4000 5000 600005101520253035404550Transmition LossFrequencyTL  Single, MPP454 lining, FEM, Flow velocity 20 m/sSingle, MPP454 lining, EXP, Flow velocity 20 m/smpp454Flow VS  No Mean flow0 1000 2000 3000 4000 5000 600005101520253035404550Transmition LossFrequencyTL  Single, No lining, EXP, No flowSingle, MPP454 liing,EXP, No FlowSingle, MPP454 lining, EXP, Flow velocity 20 m/s Measurement VS Predictionmpp454 Measurement:1. Internal design: Dual Muffler using MPP divider132.0 cm9.6 cmmpp454Mpp273, 4542.0 cm9.6 cmmpp454Rigid Divider MPP was used to divide the chamber into two instead of using a rigid dividerDual chamber using MPP dividerDual chamber using rigid divider0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000010203040506070Transmition Loss - Double chamber at 2cm from the downstreamFrequency [Hz]TL [dB]  Single Chamber FEMDouble Chamber FEM0 2000 25 0 3 0 35 0 4000 4500 5 00010203040506070Transmition Loss - Double chamber at 2cm from the downstreamFrequency [Hz]TL [dB]  Single Chamber FEMDouble Chamber FEMDouble Chamber 273 Rayls MPP dividerDouble Chamber 454 Rayls MPP divider0 1000 2000 3000 4000 5000 600005101520253035404550Frequnecy [Hz]TL [dB]Transmission Loss  Double MPP454 divider, MPP454 lining, No flow, EXPDouble MPP454 divider, MPP454 lining, No flow, FEMMPP Dual chamber with MPP lining (No mean flow)142.0 cm9.6 cmmpp454MPP 454No flow2.0 cm9.6 cmmpp454 MPP 454No flowImproves minima !!0 1000 2000 3000 4000 5000 600005101520253035404550Frequency [Hz]TL [dB]Transmission Loss  Double MPP454 divider, FEMDouble MPP454 divider, EXP0 1000 2000 3000 4000 5000 600005101520253035404550Frequency [Hz]TL [dB]Transmission Loss  MPP dual chamber, MPP454lining, EXP, flow: 20m/sMPP dual chamber, MPP454lining, FEM, flow: 20m/sMPP Dual  chamber with MPP l ining (Mean f low)152.0 cm9.6 cmNo mean flow Mean flow0 1000 2000 3000 4000 5000 600005101520253035404550Frequnecy [Hz]TL [dB]Transmission Loss  Double MPP454 divider, MPP454 lining, No flow, EXPDouble MPP454 divider, MPP454 lining, No flow, FEM Measurement:  TL at frequency region below 2500 Hz was affected by flow effect2. Internal design: Inlet and outlet extension16MPP 454Hole diameter [μm] 103.6Thickness [mm] 0.35Flow resistance [Rayls] 4540 1000 2000 3000 4000 500001020304050607080Transmition LossFrequency [Hz]TL [dB]  A TypeB TypeC TypeD TypeLee et al. (NoiseCon 14)PreviousSuggested designCurrent work with inlet/outlet extensions0 1 0 2 0 3 0 4 0 5 001020304050607080Transmition Lo sFrequency [Hz]TL [dB]  A TypeB TypeC TypeD TypeL e et al. (NoiseCon 14)TL [dB]00 00 00 00 00r iti  sr  [ ]TL [dB]      e  t l. ( i  )iti   [ ]TL [dB]       t l. i  Type C muffler with flow effects170 1000 2000 3000 4000 5000 60000102030405060Frequency [Hz]TL [dB]Transmission loss  C Type, FEM, no mean flowC Type, EXP, no mean flow0 1000 2000 3000 4000 5000 60000102030405060Frequency [Hz]TL [dB]Transmission loss  C Type, FEM, flow velocity: 20m/sC Type, EXP, flow velocity: 20m/sC4.5 cm 2.0 cm9.6 cmType C muffler with No mean flow effectMeasurement VS PredictionType C muffler with Mean flow effectMeasurement VS Prediction NO significant difference in TL at this mean flow velocity with low Mach numberComparison results (Type C vs MPP dual chamber)180 1000 2000 3000 4000 5000 600005101520253035404550Frequency [Hz]TL [dB]Transmission Loss  C Type, EXP, no mean flowC Type, EXP, flow velocity: 20m/sMPP dual chamber, MPP454 lining, EXP, No flowMPP dual chamber, MPP454lining, EXP, flow: 20m/s4.5 cm 2.0 cm9.6 cm2.0 cm9.6 cmMPP 454Type C MufflerMPP dual chamber mufflerVS.Conclusion and Future work19 Design of acoustic silencers that attenuate noise efficiently over the speech interference range were suggested by FEM and verified experimentally. Internal structure designs such as inlet/outlet extensions and MPP divided chambers were considered.  Mean flow effects in the muffler were considered and it was found that the mean flow with relatively low Mach number did not affect the acoustic performance of the mufflers of suggested designs significantly.  More optimized internal designs of the muffler will be considered in the future. Different combinations of inlet and outlet extension lengths combining with MPP lining. Multi-layer linings will be considered in multi-chamber mufflers.

Design of an Acoustic Silencer with Microperforated Elements Considering Flow Effects

https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=1113&amp;context=herrick

Design of an Acoustic Silencer with Microperforated Elements Considering Flow Effects

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