1/10. 10dB. Jacob (7)

. (). () db (3) (4) (5)(6) Jacob (7) Hz db [m/s] W H L [m] [db] [%] [%] 83.3 3..5 75dB(A).7%.% Audi AG 83.3 3.4.79 78dB(A) ----- ---- 35.4.4 48dB(A) ----- ---- 5.5.5.5 6dB(A).%.5% Controller 3-D Traverse Unit Low-speed test section 5 5 6, Umax=3m/s,u'/Uo<.% Contraction nozzle 9: Sound absorber Semi-anehoic chamber Concrete wall Guide vane (Fixed) Screens (a) Nozzle Bluff body Screens Guide vane (Moved) Silencer SA H G Guide vane (Fixed) Settling chamber Silencer SA Contraction nozzle 9: A Fan 37kw Return duct High-speed test section 5 5 5 Umax=5m/s,u'/Uo<.5% Control room F B Fan room E Silencer RA Sound absorber Flow meters Guide vane (Moved) Silencer RA C D (b) Potential core Shear layer Nozzle Potential core Flat plate Flat plate Bluff body Boundary layer /

3. 3. PIV(Particle Image Velocimetry) PTV(Particle Tracking Velocimetry) PIV () () 3 (8) (9) Prong φ. Ceramic Tube φ.9.5..7 6 8 Pressure Holes φ.4..4 φ 4 () Steel Tube φ.6 (34.3) 54.8 (.) φ 7 /4inch Condenser Microphone 3 4 3. () () (3) ( ) (3) () 5 6 7 () Brass Chamber φ= Target Probe φ=5 ReferenceMicrophone φ=4 fr a fr = π V S ( δ + m) φ=3 φ=45 S δ a m.8 Speaker Unit G = log [( f / fr) ] + (ξf / fr ) 5 φ = tan / ξ( f / f ) ( f / f r r)

Gain [db] 5 5-5 - -5 Re= 4 4 4 4 5.4 5 =. Phase [deg] 8 6 4 - -4-6 -8 Re= 4 4 4 4 5.4 5 =. - Frequency f [Hz] - Frequency [Hz] 6 7 () 3.3 8 () 9 8 9 3.4 Hz khz khz SN 4 ζ (3) r ξ = () λ π r f r π f r log = log db () λ a π db (4) 3/

(5)(6)(7) (8)(9) (8) Phased Array (9) Phased Array ()()() ()() cm khz, Phased Array 8 Phased Array B&K Müller-BBM NASA 49 6 96 64 /4inch /4inch /4inch /inch /4 inch X (.7m) ---------- ---------- cm / khz / ( 3 ) / 5kHz 5kHz 8kHz 5kHz 3kHz 4kHz Nozzle Flow 5m/s.9.8.7.6.5.4.3 97 96.5 96 95.5 95 94.5 94 93.5 93 9.5 9 9.5 9 9.5 9.. Pantograph Microphones -.4 -.3 -. -....3.4 3.5 4/

(3) Lighthill-Curle (4) α C LR ρ DLSt U 6 p( r) = (3) 6 a r P a D L r U St C LR p ( r) α C LR amρ DLSt U 6 rm =. (4) pm ( r) αm C m a m DmLmStm LR Um 6 r ρ m (4) SPLe = SPL m amρ U D Φ + log + 6log + log log + ρm m m m r r log (5) a U D Φm (5) 4 5 6 6 6 3 5 ( 3) (5) (5) 6 Φ log = 5log(Re) (6) Φm 5 (5) 6 Dm U f = fm (7) D Um (7) A 4 5 6 (3) Strouhal Number S t.6.5.4.3.. Square Cylinder (Norberg) Square Cylinder (Fujita et al.) Circular Cylinder (Norberg) Circular Cylinder (Gerrard) Circular Cylinder (Present Exp.) Circular Cylinder (Fujita et al.) Sub-critical Region Square Cylinder Reynolds Number Re R.M.S Lift Coefficient CLrm s.. Circular Cylinder (Norberg & Sunden) Circular Cylinder (Gerrard) Circular Cylinder (Present Exp.) Reynolds Number Re (6) (9) (3) 3 5/

- - -3-4 -5-6 4 8 6 35 63 5 5 5-5.5 -.9. 5-44.7 5-8.6 5.3 3.5-39.4 35-6.6 35. 4-34.6 4-4.8 4. 5-3. 5-3. 5.5 63-6. 63 -.9 63 -. 8 -.5 8 -.8 8 -. -9.. -.5 5-6. 5.6 5-4.3 6-3.4 6. 4 A /-scale Model /6-scale Model Relative Noise Level [db(a)] - - -3-4 -5-6 PS:V=69.4,/ Scale Model, Measured by Normal Microphone at 6m from center of the wind / Model /6 Model -7 / Model /5 Model -8 /5-scale Model.5 3.5 5 8 5 35 5 8 5 35 5 /3 Octave Band Center Frequency [Hz] 8 5 6 (7) (U=75m/s) U=5m/s A A (7) (3) / 4. 7 () 7km 75m/s 8 8 () f*=.4 6.5k-4kHz (3) 6/

(3) (33) (34) Noise Level db(a) 8 7 6 5 Overall Pantographs Wheel-rails Leading head Relative SPL [db(a)] - - 35 km /h 4 Time -3 /3 O ctave band center frequency [H z] 7 8 5. 5. Lighthill N-S Lighthill Lighthill a xj xixj t ρ = T ij a ρ T ij Lighthill T ij = ρ uiuj + u x u x 3 u x i j k ( p a ρ) δij + µ + µδij (9) j i k u i p Lighthill (8) Curle Lighthill xi fi pa( x) = 4πax t f i = i n PdS S P a f i P n i Lighthill-Curle Lighthill-Curle D L Phillips (35) L c fi pa ( x) = LLc xi () 6πax4 t (8) 7/

P Lc C ( f ) = C( f ) dζ () Lc 3 Gij( f ) C( f ) = 4 Gi( f ) Gj( f ) ζ G ij (f) G i (4) D= 4 mm L=5 mm / mm Helmholtz 38 Hz 8.75 Hz 6.5 Hz () L c 5 Lighthill-Curle L c Fujita (36) Lighthill-Curle Lighthill-Curle ( ) Flow.375D Pressure Ports d= mm D=4 mm Z Z=5mm Y L=5 mm X Z=-5mm Pressure Port D=4 mm Microphone Amplifier / inch Microphone SPL (db) 7 6 5 4 3 Curle's Equation Measurement..4.6.8. Dimensionless frequency f* Re=4 4 U=5. m/s D=.4 m 9 Lighthill-Curle 8/

Y/D Peak Level[dB] 9 8 7 6 5 4 Peak Level St Peak Level U 6 3. Reynolds Re number Re.5.45.4.35.3.5..5 Strouhal St[-] number St Coherence Function C.8.6.4. -4-4 Dimensionless spanwize spacing X/D Re 5. Lighthill-Curle (37)(38) Coherent Output Power COP A,B C C B B A Coherent Output Power Lighthill-Curle 5mm X Z Y X Ps X/D=.5 7. Y/D=-.4.4 69 5kHz (39) Re=4. 4 6dB 64dB X/D=.5. Y/D=±.4 (39) ( 4 ) LES (4) Re.5x5 3.x5 3.x5 3.5x5 3.7x5 4.x5 4.9x5 7.4x5.x6.x6.5x6.7x6.x6.5.5.5 -.5 - -.5 55 55 45 5 5 45 45 5 5 45.5 -.5 - -.5 - - -.5.5.5.5 3 3.5 -.5.5.5.5 3 3.5 X/D X/D 3 4 9/

db 5. () Kaji.S, 6th AIAA Aeroacoustic conference, AIAA Paper -Keynote, () (), 6 (996) (3) Nishimura, N., et al., 5th AIAA Aeroacoustic conference, AIAA Paper 99-847, (999) (4) Fujita, H., et al., Proc. INTER-NOISE93 (993), 787 79 (5) Fujita, H., et al., Proc.INTER-NOSIE96 (996), 7 3 (6) 3, 5 (993), 58 6 (7) Jacob, M.C., et al., 6th AIAA Aeroacoustic conference, AIAA Paper -, () (8) 3, 3, (99), 6 65 (9) Toyoda, K., et al., Applied Scientific Research 53 (994), 37 48, () 3,,6-59 B (995), 437 4379 () Fujita,H., et al., 4 th AIAA/CEAS Aeroacoustic Conference, AIAA Paper 98-369 (998) () Iida, A., et al., Proc. INTER-NOISE '94 (994), 63 68. (3) Fujita, H., and Kovasznay, L.S.G., :AIAA, (974),6 (4) 3, 6-64B (996),46 467, (5) Takano, Y., JSME International Journal (C), 4(), (998), 46 5 (6) Takano, Y., et al., Proc. INTER-NOISE 9, (99), 75 78 (7) Michel, U., et al. 4 th AIAA/CEAS Aeroacoustic Conference, AIAA Paper 98-336 (998) (8) Nakamura, M., et al.. Brüel & Kjær Application Note (998) (9) Jaeger, S.M., et al., 6 th AIAA/CEAS Aeroacoustic Conference, AIAA Paper -937 () () Moritoh, Y. and Zenda, Y., Japanese Railway Eng., 3, (994),5 9 (), RRR.8, (),6 9 () Sagawa, A. and Matsuo, J., 6 th AIAA/CEAS Aeroacoustic Conference, AIAA Paper -3 () (3) Iida, A., et al., 6 th AIAA/CEAS Aeroacoustic Conference, AIAA Paper -, (), (4) Curle, N., Proc. Roy. Soc. London, A3, (955),55 54, (5) Iida, A., et al., Proc. FLUCOME 97 Vol., (997), 6 (6) Norberg, B.C., J.Wind.Engineering Industrial Aerodynamics, 49 (993) 87 96 (7) Fujita, H., et al., 5 th AIAA/CEAS Aeroacoustic Conference, (999), 35 3 (8) Norberg, B.C., IUTAM Symposium Bluff-Body Wakes, Dynamics and Instabilities, (99), Pubrished by Springer-Verag. (9) Gerrard, J. H., J. Fluid Mech.,, (96), 44-56 (3) Noberg B.C. and Sundén, J. Fluids and Structures, (987), 337 357 (3) Lilley, G.M., 4 h AIAA/CEAS Aeroacoustic Conference, AIAA Paper 98-34 (998) (3) SP-4 (999),9 (33) 64-67 B (998), 48 54 (34) 66-65 B () (35) Phillips, O.M., J. Fluid Mech., -6 (956), 67 64 (36) Fujita, H., et al., 6 th AIAA/CEAS Aeroacoustic Conference, AIAA Paper -, () (37), 4, 6-569 B (994), 6 3 (38) Kato, C., et al., 6 th AIAA/CEAS Aeroacoustic Conference, AIAA Paper -94, () (39) Iida, A., et al., JSME International Jounal, (B) 4() (999), 596 64 (4), Vol. 78 (),7 /