Kyushu University Academic Staff Educational and Research Activities Database
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Toshiyuki Aoki Last modified date:2018.06.19



Graduate School
Undergraduate School


E-Mail
Homepage
http://mac507.ence.kyushu-u.ac.jp/
High-Speed Gas Dynamics Lab. .
Phone
092-583-7589
Fax
092-583-7589
Academic Degree
Doctor of Engineering
Country of degree conferring institution (Overseas)
No
Field of Specialization
Compressible Fluid Dynamics, Aeroacoustics
Total Priod of education and research career in the foreign country
01years06months
Outline Activities
●Shock wave/boundary-layer interaction in a supersonic duct
●Shock-train in a supersonic duct
●Shock associated aerodynamic noise in a supersonic jet
●Compound choking phenomena of multi-streams
●Aerodynamic noise from high-speed railway tunnel
Research
Research Interests
  • Investigation of unsteady boundary layer measured by laser differential interferometry
    keyword : laser differential interferometry, unsteady boundary, density, wave
    1998.04~2002.03.
  • Attenuation and distortion of a compression wave propagating in a high-speed railway tunnel
    keyword : high-speed train, tunnel, micro pressure wave, pressure wave, compression wave, nonlinear
    1988.01When a high-speed train enters a tunnel, a pressure wave is generated in front of the train. This pressure wave propagates to the tunnel exit and spouts as an impulsive wave, which causes a blast sound. This impulsive wave is called micro-pressure wave. The micro-pressure wave is large in a long tunnel with the concrete slab track because the wavefront of the compression wave steepens due to nonlinear effect during propagation in tunnel. On the other hand, the micro-pressure wave is weaker in a long tunnel with the ballasted track because the wavefront is gradually eroded with distance. The compression waveform in the propagation process are studied numerically, taking both fluid friction on the wall and the effect of the ballast track into consideration. The calculated results are compared with results measured in real high-speed railway slab and ballast track tunnels of the Sinkansen line in Japan. We have suggested an alleviative method to decrease the noise of the micro-pressure wave, using the ballast effect. An experimental investigation is carried out to clarify the distortion of the pressure wave..
  • Alleviation of low frequency noise from soundproof house
    keyword : infrasound, noise, alleviation method, active noise control
    2002.04The low frequency noise is not clearly defined but is generally taken to mean noise below a frequency of about 100 to 150 Hz. Noise at frequencies below about 20 Hz is sometimes referred to as infrasound and this type of noise presents even greater difficulties in its measurement and assessment. The objective of our study is to suggest practical means of reducing the low frequency noise emanating from the opening of soundproof houses..
  • Flow mechanism and noise of supersonic jets
    keyword : supersonic jet, noise, shock wave, screech sound
    2001.01Under certain conditions, supersonic jet issuing from a supersonic nozzle invariably generates supersonic jet noise, which consists of three principal components ; the turbulent mixing noise, the broadband shock-associated noise, and the screech tones. In present study, it was experimentally investigated to the effect of nozzle lip thickness on the characteristics of supersonic jet noise. The convergent-divergent nozzle of design Mach number 2.0 was used in experiment. With two different cases in the nozzle-lip thickness, pressure ratio was varied in the range between 2.0 and 12.0. Acoustic measurements were conducted by microphones in an anechoic room, and the major structures of the supersonic jets were visualized by a Schlieren optical system for the purpose of the effect of nozzle lip thickness. The measured results show that the characteristics of supersonic jet noise, such as overall sound pressure level and screech frequency, depend upon the thickness of nozzle lip..
  • Aeroacoustic noise from propagating compression wave in high-speed railway tunnel
    keyword : high-speed train, tunnel, micro pressure wave, alleviation,
    1998.01When a high-speed railway train enters a tunnel, a compression wave is generated ahead of the train and propagates along the tunnel. This wave subsequently emerges from the exit portal of the tunnel as an impulse sound which may cause noise problems in the surrounding area. During the process of reflection and radiation, the flow at tunnel exit is very complex due to three-dimensional phenomena. The present paper studies the reflection process of a propagating compression wave from a tunnel exit and the generation mechanism of an impulse sound emitted from the tunnel exit. Three-dimensional numerical analysis is carried out for the discharge of a propagation compression wave from the tunnel exit. The experimental analysis is carried out on the discharge of a compression wave from an open end of a tube, which has one or two baffle plates at the end. The process of generating the impulse sound and the influence of the shape of tunnel exit are discussed..
Academic Activities
Papers
1. Anyoji Masayuki, Issei Tabaru, Toshiyuki Aoki, Reducing Jet Noise in Over-Expanded Nozzle Flow, Proc. 6th Asian Joint Workshop on Thermophysics and Fluid Science, 1-6, 2016.09.
2. Kosuke Satoh, Kohei Satoh, Nobuaki Kondo, Toshiyuki Aoki, Aerodynamic Sound and Flow Field Generated from Combination Taped Cylinder, Proc. 5th Asian Joint Workshop on Thermophysics and Fluid Science, 1-6, 2014.09, This study deals with the aerodynamic sound observed in the Aeolian tone. One of the problems with the aerodynamic sound, noise reduction along a railway line is very important for further speed-up of a high-speed train. In particular, the aerodynamic sound from a pantograph is one of the main noise sources; therefore it has become increasingly important to reduce the foregoing noise. In recent years, several researchers study the aerodynamic sound reduction by a pantograph – application of porous material, pile-fabrics, development of the pantograph cover and single-arm type design. As one method for the aerodynamic sound reduction, this study apply to the taped cylinder by a pantograph arm was proposed. Experimental investigation is carried out to clarify the aerodynamic sound and flow field by combination taped cylinders and compared with those of straight cylinder..
3. Yuki Tagita, Toshiyuki Aoki, Taro Handa, Nobuaki Kondo, Investigation of Noise Phenomena with Two-Dimensional Convergent-Divergent Nozzle, Proc. 5th Asian Joint Workshop on Thermophysics and Fluid Science, 1-6, 2014.09, This paper describes experimental work to investigate noise phenomenon in transonic flow that is discharged from a convergent-divergent nozzle. The noise phenomenon of flow is generated by an emission of ‘transonic tones’. Transonic tone is different from the screech tone due to the shock-cell structures in a jet, and originates in the shock wave in the nozzle. To investigate this noise phenomenon, we conducted noise measurement, flow visualization, and static pressure measurement. In the past study, we confirmed close correlations between the transonic tone frequency and wall pressure fluctuation or shock oscillation. Furthermore, we confirmed the involution of the flow occurred around the nozzle lip. In this study, we investigated the influence that a nozzle rip thickness gave to the transonic tone. We tested it on the nozzle rip thickness of 4 patterns, and we confirmed that transonic tone is related to the thickness of the nozzle lip..
4. Takuya Ogawa, Toshiyuki Aoki, Hiromu Yamasaki, Nobuaki Kondo, Masaki Ogishima, Characteristic on Nonsteady Boundary Layer induced by Propagating Pressure Wave in Long Tube, Proc. 5th Asian Joint Workshop on Thermophysics and Fluid Science, 1-6, 2014.09, A pressure wave is generated ahead of a high-speed train, while entering a tunnel. This pressure wave propagates to the tunnel exit and spouts out as a micro pressure wave, causing an exploding sound. In order to estimate the magnitude correctly, the mechanism of the attenuation and distortion of a pressure wave propagating along a tunnel must be understood and experimental information on these phenomena is required. An experimental and numerical investigation is carried out to clarify the mechanism of the propagating pressure wave in a long tube. The final objective of our study is to understand the mechanism of the attenuation and distortion of propagating pressure waves in a tunnel. In the present paper, experimental investigations are carried out on the transition of the unsteady boundary layer induced by a propagating pressure wave and the density distribution of the boundary layer by means of a developed laser differential interferometry technique..
5. Seoungyoung Shin, Akira Mtsunaga, Hiroyuki Marubayashi, Toshiyuki Aoki, Effects of Nozzle-Lip Length on Reduction of Transonic Resonance in 2D Supersonic Nozzle, Open Journal of Fluid Dynamics, DOI: 10.4236/ojfd.2013.32A011, 3, 2A, 69-74, 2013.07, The present paper describes an experimental work to investigate a reduction of transonic resonance by controlling the nozzle-lip length of 2 Dimensional converging-diverging nozzle. The transonic resonance is generated by an emission of strong acoustic tones due to the unsteadiness of the shock. In this study, the nozzle pressure ratio is varied to obtain the shock-containing condition in nozzle divergent section which is operated in the range between 1.4 and 2.2 nozzle pressure ratios. A Schlieren optical system is used to visualize the flow field or analyze the shock oscillation by using a high-speed video camera and acoustic measurements are employed to compare the sound spectra level of each case. The experimental results have seen a decrease in transonic resonance when a large separation zone is located at the same side of long nozzle-lip attached. In this case, the amplitude of shock oscillation and wall static pressure oscillation is also decreased. .
6. Seoungyoung Shin, Akira Mtsunaga, Hiroyuki Marubayashi, Toshiyuki Aoki, Effects of Asymmertic Nozzle-Lip Length on Reduction of Transonic Resonance in 2D Supersonic Nozzle, Proceedings of 11th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows , 1-5, 2013.05.
7. Kohei Sato, Ryutaro Machida, Toshiyuki Aoki, Aerodynamic Sound and Flow Field Generated from Combinational Inclined Tapered Cylinder, Open Journal of Fluid Dynamics, doi:10.4236/ojfd.2012.24A025, 2, 222-227, 2012.12, This study deals with the aerodynamic sound, especially the Aeolian tone. One of the problems with the aerodynamic sound, noise reduction along a railway line is significant engineering issue for further speed-up of a high-speed train. In particular, a pantograph is one of the main aerodynamic noise sources of a high-speed train. As one of the methods for the aerodynamic noise reduction, this study proposes the tapered cylinder by a pantograph. In this paper, the aerody- namic sound and the wake flow of the combinational inclined circular cylinder and tapered cylinder are experimentally and numerically investigated in knuckle upstream and knuckle downstream. Also, we suggest that the surface of grooves such as wood grain interacts with the aerodynamic sound generated from the model. Here, it is considered that the comparison of aerodynamic sound between the model with grooves and without grooves. Consequently, reduction of the maximum aerodynamic sound is possible for the tapered cylinder in the case of knuckle downstream. Further- more, the noise reduction method is effective that the model surface with grooves such as wood grain..
8. Toshiyuki TANAKA, Toshiyuki Aoki, Characteristics of Unsteady Boundary Layer Induced by the Compression Wave Propagating in a Tunnel, Open Journal of Fluid Dynamics, doi:10.4236/ ojfd.2012.24A030, 2, 257-263, 2012.12, A compression wave is generated ahead of a high-speed train, while entering a tunnel. This compression wave propa- gates to the tunnel exit and spouts out as a micro pressure wave, causing an exploding sound. In order to estimate the magnitude correctly, the mechanism of the attenuation and distortion of a compression wave propagating along a tunnel must be understood and experimental information on these phenomena is required. An experimental and numerical in- vestigation is carried out to clarify the mechanism of the propagating compression wave in a tube. The final objective of our study is to understand the mechanism of the attenuation and distortion of propagating compression waves in a tun- nel. In the present paper, experimental investigations are carried out on the transition of the unsteady boundary layer induced by a propagating compression wave in a model tunnel by means of a developed laser differential interferometry technique..
9. Xiao HU, Toshiyuki Aoki, Naoya TOKURA, The Feature of Weak Shock Wave Propagated in a Overlong Tunnel, Open Journal of Fluid Dynamics, doi:10.4236/ ojfd.2012.24A034, 2, 285-289, 2012.12, Many experiment researches have been developed before. But most of them were carried out with the condition that the tunnel’s ratio of length and diameter (x/D) is under 1000. Recently, the process that compression wave convents into shock wave in the overlong tunnel has also been paid attention. In this paper, features of shock wave as it propagates through a overlong tunnel is investigated, rupturing thin films at the entrance to obtain three kinds of shock wave with different intensities. Then study their features respectively during they propagates through a overlong tunnel with x/D over 6000 at most. Comprehend shock wave more deeply by comparing the results of experiments..
10. Kohei Sato, Ryutaro Machida, Toshiyuki Aoki, Aerodynamic Sound and Flow Field Generated from Combinational Inclined Tapered Cylinder, Proc. 4th Asian Joint Workshop on Thermophysics and Fluid Science, 1-6, 2012.10, This study deals with the aerodynamic sound, especially the aeolian tone. One of the problems with the aerodynamic sound, noise reduction along a railway line is significant engineering issue for further speed-up of a high-speed train. In particular, a pantograph is one of the main aerodynamic noise sources of a high-speed train. As one of the methods for the aerodynamic noise reduction, this study proposes the tapered cylinder by a pantograph. In this paper, the aerody-namic sound and the wake flow of the combinational inclined circular cylinder and tapered cylinder are experimentally and numerically investigated in knuckle upstream and knuckle downstream. Also, we suggest that the surface of grooves such as wood grain interacts with the aerodynamic sound generated from the model. Here, it is considered that the comparison of aerodynamic sound between the model with grooves and without grooves. Consequently, reduction of the maximum aerodynamic sound is possible for the tapered cylinder in the case of knuckle downstream. Further-more, the noise reduction method is effective that the model surface with grooves such as wood grain..
11. S. Shin, Makiko Yonamine, A. Tokumoto, H. Kuguyama, Toshiyuki Aoki, Experimental investigation on correlations between transonic tone and flow oscillation in a supersonic nozzle, Proc. 4th Asian Joint Workshop on Thermophysics and Fluid Science, 1-6, 2012.10, The present paper describes an experimental work to investigate characteristics and generation mechanism of the transonic tone. And this work attempts to correlate the transonic tone to flow oscillation from a shock-containing convergent-divergent nozzle. A wall pressure measurement, acoustic measurement and a high speed video camera for Schlieren visualization to visualize shock oscillations are used to investigate the tone generation mechanism. And all measurements are set up to get data at the same time for find the correlations between transonic tone and wall static pressure oscillation. For the conditions of this study the transonic tone takes place in one or two stages or not occurs. And it is found that there is close correlation between transonic tone frequency and wall pressure fluctuation or shock oscillation each other when the transonic tone is diffusing from the nozzle..
12. Toshiyuki TANAKA, Toshiyuki Aoki, Characteristics of unsteady boundary layer induced by the compression wave propagating in a tunnel, Proc. 4th Asian Joint Workshop on Thermophysics and Fluid Science, 1-6, 2012.10, A compression wave is generated ahead of a high-speed train, while entering a tunnel. This compression wave propa-gates to the tunnel exit and spouts out as a micro pressure wave, causing an exploding sound. In order to estimate the magnitude correctly, the mechanism of the attenuation and distortion of a compression wave propagating along a tunnel must be understood and experimental information on these phenomena is required. An experimental and numerical in-vestigation is carried out to clarify the mechanism of the propagating compression wave in a tube. The final objective of our study is to understand the mechanism of the attenuation and distortion of propagating compression waves in a tun-nel. In the present paper, experimental investigations are carried out on the transition of the unsteady boundary layer induced by a propagating compression wave in a model tunnel by means of a developed laser differential interferometry technique..
13. Xiao HU, Toshiyuki Aoki, Naoya TOKURA, The feature of weak shock wave propagated in a overlong tunnel, Proc. 4th Asian Joint Workshop on Thermophysics and Fluid Science, 1-6, 2012.10, Many experiment researches have been developed before. But most of them were carried out with the condition that the tunnel's ratio of length and diameter (x/D) is under 1000. Recently, the process that compression wave convents into shock wave in the overlong tunnel has also been paid attention.
In this paper, features of shock wave as it propagates through a overlong tunnel is investigated. Rupturing thin films at the entrance to obtain three kind of shock wave with different intensities. Then study their features respectively during they propagates through a overlong tunnel with x/D over 6000 at most. Comprehend shock wave more deeply by comparing the results of experiments.
.
14. Seungyoung Shin, Mkiko Yonamine, Akira Tokumoto, Hiroki Kuguyama and Toshiyuki Aoki, Experimental investigation on correlations between transonic tone and flow oscillation in a supersonic nozzle, Proc. inter・noise 2011, 2011.09.
15. Tomo ORITA, Toshiyuki AOKI, Shinsuke ISHII, and Daisuke SASA, Characteristics of nonlinear effects on the propagating compression wave in a tunnel, Proc. inter・noise 2011, 2011.09.
16. Shinichiro Nakao, Toshiyuki Aoki, Tadakazu Tanino, Takeshi Miyaguni and Kazuyasu Matsuo, A new passive control method of the pressure wave propagating through in a high speed railway tunnel, Proc. 14th International Symposium on Aerodynamics and Ventilation of Tunnels, 2011.05.
17. M. Yonamine, N. Kawashima, S. Shin, S. Jung and T. Aoki, Experimental investigation of shock oscillations and transonic tone in supersonic nozzle, Proc. 3rd Asian Joint Workshop on Thermophysics and Fluid Science, 2010.09.
18. Shinya Nakamura, Daisuke Sasa and Toshiyuki Aoki, Attenuation and Distortion of Compression Wave Propagating in Very Long Tube, Journal of Thermal Science, 20, 1, 1-5, 2011.01.
19. Shinya Nakamura, Daisuke Sasa and Toshiyuki Aoki, Attenuation and Distortion of Compression Wave Propagating in Very Long Tube, Proc. 3rd Asian Joint Workshop on Thermophysics and Fluid Science, 2010.09.
20. Toshiyuki AOKI, Masanori TANAKA and Yutaro SUGIURA, Alleviation of Low Frequency Noise from a Soundproof House by Standing Wave Control, Journal of Environment and Engineering, 5, 1, 226-230, 2010.04.
21. Makiko Yonamine, Jung Sungjae and Toshiyuki Aoki , INVESTIGATION ON TRANSONIC TONE IN SUPERSONIC NOZZLE , Proc. of The 6th International Congress on Sound and Vibration, 2009.07.
22. M. Yonamine, S. Jung and T. Aoki, Study on Transonic Tone in Axisymmetric Supersonic Nozzle, Proc. of The 9th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows (ISAIF9), 2009.09.
23. Toshiyuki AOKI, Kouji MIURA and Shinsuke ISHII, Characteristics of Compression Wave Propagating in a Very Long Railway Tunnel, Proc. of The 9th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows (ISAIF9), 2009.09.
24. Yong-Hun Kweon , Toshiyuki Aoki and Heuy-Dong Kim, Control of Supersonic Jet Noise Using Mesh Screen Device, Proc. of The 9th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows (ISAIF9), 2009.09.
25. T. Aoki, An Experimental Study on Transonic Resonance in Two Dimensional Supersonic Nozzle, Proc. of the 12th Asian Congress of Fluid Mechanics, Daejeon, Korea (2008), 2008.08.
26. S.J. Jung, T. Aoki, H.D. Kim and T. Setoguchi, AN EXPERIMENTAL STUDY ON TRANSONIC TONE IN SUPERSONIC NOZZLE FLOW, Proc. 2nd Asian Joint Workshop on Thermophysics and Fluid Science, 2008.05.
27. T. Aoki, J.Yamamoto and K. Nagatani, CHARACTERISTICS OF A COMPRESSION WAVE PROPAGATING OVER POROUS PLATE WALL IN A HIGH-SPEED RAILWAY TUNNEL, Proc. 2nd Asian Joint Workshop on Thermophysics and Fluid Science, 2008.05.
28. T. Aoki, J.Yamamoto and K. Nagatani, Characteristics of a compression wave propagating over porous plate wall in a high-speed railway tunnel, Journal of Thermal Science, , Vol.17, No.3, pp218-223, 2008., 2008.10.
29. S.J. Jung, T. Aoki, H.D. Kim and T. Setoguchi, AN EXPERIMENTAL STUDY ON TRANSONIC TONE IN SUPERSONIC NOZZLE FLOW, Proceedings of 2nd Asian Joint Workshop on Thermophysics and Fluid Science,, pp198-201, 2008., 2008.05.
30. T. Aoki, J.Yamamoto and K. Nagatani, CHARACTERISTICS OF A COMPRESSION WAVE PROPAGATING OVER POROUS PLATE WALL IN A HIGH-SPEED RAILWAY TUNNEL, Proceedings of 2nd Asian Joint Workshop on Thermophysics and Fluid Science, pp117-121, 2008., 2008.05.
31. Kweon,Y.H.,Jung,S.J.,Miyazato,Y.,Aoki,T.,Kim,H.D.,and Setoguchi,T., Shock-Associated Noise Reduction in Supersonic Jets Using a Wire Device, 1st the Asian Joint Workshop on Thermophysics and Fluids Science, pp.174-177, 2006.06.
32. Kweon,Y.H., Miyazato,Y.,Aoki,T.,Kim,H.D.,and Setoguchi,T., Control of supersonic jet noise using a wire device, Journal of Sound and Vibration, Vol.297.pp.167-182, 2006.03.
33. Kweon,Y.H.,Miyazato,Y.,Aoki,T.,Kim,H.D.,and Setoguchi,T., Experimental investigation of nozzle exit reflector effect on supersonic jet, Shock Waves, Vol.15,pp.229-239, 2006.06.
34. T.Aoki, S.Nakao, K.Matsuo, Ballast effect on distortion of propagating compression wave in high-speed railway tunnel, Proc. 22nd Int. Symp. on shock waves, 1-6, 1999.11.
Presentations
1. Aerodynamic Sound Generated from Combinational Inclined Circular Cylinder with Step Ring.
2. Characteristic on Unsteady Boundary Layer Induced by Propagating Pressure Wave in Long Tube.
3. Characteristic on Unsteady Boundary Layer Induced by Propagating Pressure Wave in Long Tube.
4. Characteristic on Unsteady Boundary Layer Induced by Propagating Pressure Wave in Long Tube.
5. Characteristic on Unsteady Boundary Layer Induced by Propagating Pressure Wave in Long Tube.
6. Anyoji Masayuki, Issei Tabaru, Toshiyuki Aoki, Reducing Jet Noise in Over-Expanded Nozzle Flow, 6th Asian Joint Workshop on Thermophysics and Fluid Science, 2016.09.
7. Aerodynamic Sound Generated from Combinational Inclined Circular Cylinder with Step Ring.
8. Characteristic on Unsteady Boundary Layer Induced by Propagating Pressure Wave in Long Tube.
9. Yuki Tagita, Toshiyuki Aoki, Taro Handa, Nobuaki Kondo, Investigation of Noise Phenomena with Two-Dimensional Convergent-Divergent Nozzle, 5th Asian Joint Workshop on Thermophysics and Fluid Science, 2014.09, This paper describes experimental work to investigate noise phenomenon in transonic flow that is discharged from a convergent-divergent nozzle. The noise phenomenon of flow is generated by an emission of ‘transonic tones’. Transonic tone is different from the screech tone due to the shock-cell structures in a jet, and originates in the shock wave in the nozzle. To investigate this noise phenomenon, we conducted noise measurement, flow visualization, and static pressure measurement. In the past study, we confirmed close correlations between the transonic tone frequency and wall pressure fluctuation or shock oscillation. Furthermore, we confirmed the involution of the flow occurred around the nozzle lip. In this study, we investigated the influence that a nozzle rip thickness gave to the transonic tone. We tested it on the nozzle rip thickness of 4 patterns, and we confirmed that transonic tone is related to the thickness of the nozzle lip..
10. Kosuke Satoh, Kohei Satoh, Nobuaki Kondo, Toshiyuki Aoki, Aerodynamic Sound and Flow Field Generated from Combination Taped Cylinder, 5th Asian Joint Workshop on Thermophysics and Fluid Science, 2014.09, This study deals with the aerodynamic sound observed in the Aeolian tone. One of the problems with the aerodynamic sound, noise reduction along a railway line is very important for further speed-up of a high-speed train. In particular, the aerodynamic sound from a pantograph is one of the main noise sources; therefore it has become increasingly important to reduce the foregoing noise. In recent years, several researchers study the aerodynamic sound reduction by a pantograph – application of porous material, pile-fabrics, development of the pantograph cover and single-arm type design. As one method for the aerodynamic sound reduction, this study apply to the taped cylinder by a pantograph arm was proposed. Experimental investigation is carried out to clarify the aerodynamic sound and flow field by combination taped cylinders and compared with those of straight cylinder..
11. Takuya Ogawa, Toshiyuki Aoki, Hiromu Yamasaki, Nobuaki Kondo, Masaki Ogishima, Characteristic on Nonsteady Boundary Layer induced by Propagating Pressure Wave in Long Tube, 5th Asian Joint Workshop on Thermophysics and Fluid Science, 2014.09, A pressure wave is generated ahead of a high-speed train, while entering a tunnel. This pressure wave propagates to the tunnel exit and spouts out as a micro pressure wave, causing an exploding sound. In order to estimate the magnitude correctly, the mechanism of the attenuation and distortion of a pressure wave propagating along a tunnel must be understood and experimental information on these phenomena is required. An experimental and numerical investigation is carried out to clarify the mechanism of the propagating pressure wave in a long tube. The final objective of our study is to understand the mechanism of the attenuation and distortion of propagating pressure waves in a tunnel. In the present paper, experimental investigations are carried out on the transition of the unsteady boundary layer induced by a propagating pressure wave and the density distribution of the boundary layer by means of a developed laser differential interferometry technique..
12. Investigation of aeroacoustic noise with two-dimensional convergent-divergent nozzle
.
13. Characteristic of Unsteady Boundary Layer Induced by Propagating Pressure Wave in Long Tube.
14. Characteristic of Unsteady Boundary Layer Induced by Propagating Pressure Wave in Long Tube
.
15. Characteristic of Unsteady Boundary Layer Induced by Propagating Pressure Wave in Long Tube
.
16. Characteristics of weak pressure wave propagated in overlong tube including porous wall.
17. Aerodynamic Sound and Flow Field Generated from Combination Inclined Cylinder with tape.
18. Experimental investigation of transonic tone in supersonic nozzle
.
19. Aerodynamic Sound and Flow Field Generated from Combinational Inclined Cylinder.
20. Seoungyoung Shin, Akira Mtsunaga, Hiroyuki Marubayashi, Toshiyuki Aoki, Effects of Asymmertic Nozzle-Lip Length on Reduction of Transonic Resonance in 2D Supersonic Nozzle, The 11th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows, 2013.05.
21. Kohei Sato, Ryutaro Machida, Toshiyuki Aoki, Aerodynamic Sound and Flow Field Generated from Combinational Inclined Tapered Cylinder, 4th Asian Joint Workshop on Thermophysics and Fluid Science, 2012.10, This study deals with the aerodynamic sound, especially the aeolian tone. One of the problems with the aerodynamic sound, noise reduction along a railway line is significant engineering issue for further speed-up of a high-speed train. In particular, a pantograph is one of the main aerodynamic noise sources of a high-speed train. As one of the methods for the aerodynamic noise reduction, this study proposes the tapered cylinder by a pantograph. In this paper, the aerody-namic sound and the wake flow of the combinational inclined circular cylinder and tapered cylinder are experimentally and numerically investigated in knuckle upstream and knuckle downstream. Also, we suggest that the surface of grooves such as wood grain interacts with the aerodynamic sound generated from the model. Here, it is considered that the comparison of aerodynamic sound between the model with grooves and without grooves. Consequently, reduction of the maximum aerodynamic sound is possible for the tapered cylinder in the case of knuckle downstream. Further-more, the noise reduction method is effective that the model surface with grooves such as wood grain..
22. Xiao HU, Toshiyuki Aoki, Naoya TOKURA, The feature of weak shock wave propagated in a overlong tunnel
, 4th Asian Joint Workshop on Thermophysics and Fluid Science, 2012.10, Many experiment researches have been developed before. But most of them were carried out with the condition that the tunnel's ratio of length and diameter (x/D) is under 1000. Recently, the process that compression wave convents into shock wave in the overlong tunnel has also been paid attention.
In this paper, features of shock wave as it propagates through a overlong tunnel is investigated. Rupturing thin films at the entrance to obtain three kind of shock wave with different intensities. Then study their features respectively during they propagates through a overlong tunnel with x/D over 6000 at most. Comprehend shock wave more deeply by comparing the results of experiments.
.
23. Toshiyuki TANAKA, Toshiyuki Aoki, Characteristics of unsteady boundary layer induced by the compression wave propagating in a tunnel, 4th Asian Joint Workshop on Thermophysics and Fluid Science, 2012.10, A compression wave is generated ahead of a high-speed train, while entering a tunnel. This compression wave propa-gates to the tunnel exit and spouts out as a micro pressure wave, causing an exploding sound. In order to estimate the magnitude correctly, the mechanism of the attenuation and distortion of a compression wave propagating along a tunnel must be understood and experimental information on these phenomena is required. An experimental and numerical in-vestigation is carried out to clarify the mechanism of the propagating compression wave in a tube. The final objective of our study is to understand the mechanism of the attenuation and distortion of propagating compression waves in a tun-nel. In the present paper, experimental investigations are carried out on the transition of the unsteady boundary layer induced by a propagating compression wave in a model tunnel by means of a developed laser differential interferometry technique..
24. S. Shin, Makiko Yonamine, A. Tokumoto,, H. Kuguyama, Toshiyuki Aoki, Experimental investigation on correlations between transonic tone and flow oscillation in a supersonic nozzle, 4th Asian Joint Workshop on Thermophysics and Fluid Science, 2012.10, The present paper describes an experimental work to investigate characteristics and generation mechanism of the transonic tone. And this work attempts to correlate the transonic tone to flow oscillation from a shock-containing convergent-divergent nozzle. A wall pressure measurement, acoustic measurement and a high speed video camera for Schlieren visualization to visualize shock oscillations are used to investigate the tone generation mechanism. And all measurements are set up to get data at the same time for find the correlations between transonic tone and wall static pressure oscillation. For the conditions of this study the transonic tone takes place in one or two stages or not occurs. And it is found that there is close correlation between transonic tone frequency and wall pressure fluctuation or shock oscillation each other when the transonic tone is diffusing from the nozzle..
25. Influence on Waveform of Unsteady Flow Induced by Propagating Compression Wave in a Tube.
26. Characteristics of Propagating Shock Wave in a Very Long Tube.
27. Research on Vibration of Shock Waves Caused in a Supersonic Nozzle and Generated Noise.
28. Effects of initial waveform on the nonlinear propagation of compression wave in a tunnel.
29. Characteristics of Propagating Compression Wave in a Very Long Tube.
30. Characteristics of a propagating compression wave in a tunnel with a porous plate wall.
31. Characteristics of Propagating Compression Wave in a Very Long Tunnel.
32. Characteristics of Propagating Compression Wave in a Very Long Tube.
33. Acoustic Characteristics of Supersonic Jet from Laval Nozzle with Duct.
34. Acoustic Characteristics of Supersonic Jet from Laval Nozzle with Duct.
35. A Study on a Shock Associated Noise in Over-Expanded Supersonic Jets.
36. A Study on a Shock Associated Noise in Over-Expanded Supersonic Jets.
37. Study of supersonic jet noise reduction using a mesh screen device.
38. An Experimental Study on a Noise Phenomenon in Over-Expanded Supersonic Jets
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39. Passive control of propagating pressure wave in a tunnel with a porous plate
.
40. Alleviation of low frequency noise by the soundproof opening built in Helmholtz resonators.
41. Shock-Associated Noise Reduction in Supersonic Jets Using a Wire Device.
42. Characteristics of Propagating Compression Wave in a Tube with Various Wall Structure
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Membership in Academic Society
  • Shock Wave Research Society of Japan
  • International Shock Wave Institute (ISWI)
  • The Japan Society of Mechanical Engineering
  • THE VISUALIZATION SOCIETY OF JAPAN
  • The Institute of Electrical Engineering of Japan
Educational
Educational Activities
Graduate School: Department of Energy and Environmental Engineering
Interdisciplinary Graduate School of Engineering Sciences
Basic subject of Fluid Dynamics
Aeroacoustics
Numerical Fluid Dynamics
Experiments of High-Speed Gas Dynamics
Tutorial Exercises for Doctor thesis

Undergraduate School: Department of Energy Science and Engineering
Core seminar
Experiments of Energy System Engineering
Fluid Dynamics I
Fluid Dynamics II