Energy & Environment

Over 80 % of world energy supply is estimated to be provided by burning fossil fuels for the next tens of years according to the prediction reported by U. S. Department of Energy in 2011. The amount of available fossil fuels is limited. The net energy demands are linearly increasing. Alternative energy sources have not been matured enough (but yes, they will eventually take over combustion-related energy in a very long term). The accident of Fukushima nuclear power plant. Increasing net CO2, NOx and SOx emissions. What can we do?

MILD (Moderate or Intense Low-oxygen Dilution) combustion

[Above figure] MILD (Moderate or Intense Low-oxygen Dilution) combustion is one of potential combustion technologies for stable, high-efficiency, low-emission combustors. MILD combustion is also known as "flameless" combustion where no visible flame is observed. This image shows an instantaneous snapshot of turbulent MILD combustion simulated using state-of-the-art turbulent flow simulation technique called DNS. The temperature iso-surfaces (blue: low, red: high) show that the temperature rise does not necessarily occur in a "thin sheet" but rather volumetric. The second invariant of velocity gradient (purple iso-surfaces) shows that the turbulence decays quickly as temperature increases. However, some vortices are strong enough to penetrate into the high temperature side, which may enhance the micro-scale mixing of mixtures for stable combustion. The intense reaction rate (white) exists throughout the domain and are highly convoluted. This volumetric reaction is the unique characteristic of MILD combustion and the key to achieve "greener" combustion devices.

Table 1: Turbulent and thermochemical conditions for methane-air MILD premixed (A1, A2, B1) and conventional premixed (C) cases. The above image shows an instantaneous result of Case B1. These DNS data sets are available for use. Contact me for details.
CaseX_O2 phi Tr
(K)
Tp
(K)
SL
(m/s)
d_th
(m)
U/SL u'/SL l/d_F l/d_th Re_l (Taylor) Da Ka
A1 0.035 0.81500 1865 3.20 0.69E-3 9.6 6.26 10.8 1.48 96.2 (32.6) 1.72 4.78
A2 0.035 1500 1865 3.20 0.69E-3 9.6 3.80 12.3 1.70 67.0 (25.6) 3.25 2.11
B1 0.025 1500 1775 2.15 0.94E-3 15.1 9.88 6.8 1.15 96.1 (32.6) 0.69 11.9
C 0.194 600 2179 1.18 0.37E-3 3.0 2.19 12.3 2.11 38.5 (17.6) 5.64 0.92

Turbulent premixed flames exposed to strong shear layers

[Below figure] Many of turbulent premixed combustion DNS studies consider freely-propagating, statistically one-dimensional turbulent combustion, where a planar flame propagates in a homogeneous isotropic turbulence (very idealized turbulence without anisotropy). However, most of practical combustion devices involve not only turbulent flows, but also strong shear and swirl flows. As a result, flames no longer propagates freely like they would in such an ideal environment. The turbulent premixed flame exposed to strong shear layers (aka. V-shaped flame, or simply V-flame) is a turbulent premixed flame one step closer to the turbulent combustion observed in such practical combustion devices. The flame is stabilized using a hot-rod having a diameter of d. The below image enlarges three regions. The botom one shows the incoming turbulence eddies whose turbulent level is about 100 for the Reynolds number based on Taylor microscale. The middle one shows the flame just behind the anchor (hot-rod). There are still strong eddies outside and inside the flames, suggesting strong turbulence-flame interactions. Also, the effect of shear flows can be seen near the hot-rod. The top image shows the downstream region. The flame spread and is convoluted. There are still some eddies around, but they are not as many as in upstream regions. Thus, the intensity of turbulence-flame interaction differs with the streamwise distance. Like this turbulent flame, most turbulent flames in practical devices experience different level/types of turbulence depending on their locations. Turulent combustion models need to take into account these different turbulence-flame interactions involved.

Table 2: Turbulent and thermochemical conditions for hydrogen-air turbulent V-flame. The above image shows an instantaneous result of V97.
Case phi Tr
(K)
SL
(m/s)
d_th
(m)
U/SL u'/SL l/d_th Re_l (Taylor) Da Ka
V60 1.070010.34.7E-4 10.0 2.2 1.6 199.8 (60.8) 0.73 1.3
V60H 20.0 2.2 1.6 199.8 (60.8) 0.73 1.3
V97 20.0 6.0 1.5 516.2 (97.1) 0.24 6.2

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Education and professional experience

Research interests

Fluid mechanics, turbulent flows, heat transfer, computational fluid dynamics, high performance computing, laser diagnostics

Journal publications

  1. Basmil Yenerdag, Yuki Minamoto, Masayasu Shimura, Yuzuru Nada, Mamoru Tanahashi, Flame-wall interactions of lean premixed flames under elevated, rising pressure conditions, Fuel, 189 (2017) 8-14.
  2. Katsuhiro Hiraoka, Yoshitsugu Naka, Masayasu Shimura, Yuki Minamoto, Naoya Fukushima, Mamoru Tanahashi, Toshio Miyauchi, Evaluations of SGS Combustion, Scalar Flux and Stress Models in a Turbulent Jet Premixed Flame, Flow Turbulence and Combustion, 97 (4) 1147-1164 (2016).
  3. Katsuhiro Hiraoka, Yuki Minamoto, Masayasu Shimura, Yoshitsugu Naka, Naoya Fukushima and Mamoru Tanahashi, A Fractal Dynamic SGS Combustion Model for Large Eddy Simulation of Turbulent Premixed Flames, Combustion Science and Technology, 188 (9) 1472-1495 (2016).
  4. Y. Gao, Y. Minamoto, M. Tanahashi and N. Chakraborty, A priori assessment of scalar dissipation rate closure for Large Eddy Simulations of turbulent premixed combustion using a detailed chemistry Direct Numerical Simulation database, Combustion Science and Technology, 188 (9) 1398-1423 (2016).
  5. Basmil Yenerdag, Yuki Minamoto, Yoshitsugu Naka, Masayasu Shimura and Mamoru Tanahashi, Flame propagation and heat transfer characteristics of a hydrogen--air premixed flame in a constant volume vessel, International Journal of Hydrogen Energy, 41 (22) 9679-9689 (2016).
  6. Yuki. Minamoto and Jacqueline H. Chen, DNS of a turbulent lifted DME jet flame, Combustion and Flame, 169, 38-50 (2016).
  7. Y. Minamoto, K. Aoki, M. Tanahashi and N. Swaminathan, DNS of swirling hydrogen-air premixed flame, International Journal of Hydrogen Energy, 40 (39) 13604–13620 (2015). [pdf].
  8. Y. Minamoto, H. Kolla, R. W. Grout, A. Gruber and J. H. Chen, Effect of fuel composition and differential diffusion on flame stabilization in reacting syngas jets in turbulent cross-flow, Combustion and Flame, 162 (10) 3569-3579 (2015) [pdf].
  9. Y. Minamoto and N. Swaminathan, Subgrid scale modelling for MILD combustion, Proceedings of the Combustion Institute, 35 (3) 3529-3536 (2015) (Open Access).
  10. Y. Minamoto, N. Swaminathan, R. S. Cant and T. Leung, Morphological and statistical features of reaction zones in MILD and premixed combustion, Combustion and Flame, 161 (11) 2801-2814 (2014). [pdf]
  11. Y. Minamoto and N. Swaminathan, Modelling paradigms for MILD combustion, International Journal of Advances in Engineering Sciences and Applied Mathematics (invited paper), 6 (1-2) 65-75 (2014). [pdf]
  12. Y. Minamoto, N. Swaminathan, R. S. Cant and T. Leung, Reaction zones and their structure in MILD combustion, Combustion Science and Technology, 186 (8) 1075-1096 (2014). [pdf]
  13. Y. Minamoto and N. Swaminathan, Scalar gradient behaviour in MILD combustion, Combustion and Flame, 161 (4) 1063-1075 (2014). [pdf]
  14. Y. Minamoto, T. D. Dunstan, N. Swaminathan and R. S. Cant, DNS of EGR-type turbulent flame in MILD condition, Proceedings of the Combustion Institute, 34 (2) 3231-3238 (2013). [pdf]
  15. T. D. Dunstan, Y. Minamoto, N. Chakraborty and N. Swaminathan, Scalar dissipation rate modelling for Large Eddy Simulation of turbulent premixed flames. Proceedings of the Combustion Institute, 34 (1) 1193-1201 (2013).
  16. Y. Minamoto, N. Fukushima, M. Tanahashi, T. Miyauchi, T. D. Dunstan and N. Swaminathan, Effect of flow-geometry on turbulence-scalar interaction in premixed flames, Physics of Fluids, 23 (12) 125107 (2011). [pdf]

Conference presentations

  1. Yuki Minamoto and Nedunchezhian Swaminathan, Morphological features of reaction zones in MILD combustion, First Pacific Rim Thermal Engineering Conference, 14725, Hawaii, USA, Mar. 13-17, 2016.
  2. Yuki Minamoto, Kozo Aoki, Mamoru Tanahashi and Nedunchezhian Swaminathan, A DNS study on the scalar mixing mechanism in turbulent premixed swirling flames for Reynolds-averaged reaction rate modeling, First Pacific Rim Thermal Engineering Conference, 14583, Hawaii, USA, Mar. 13-17, 2016.
  3. Y. Minamoto, H. Kolla, R. W. Grout, A. Gruber and J. H. Chen, Effect of differential diffusion on flame stabilization in a syngas jet in turbulent cross-flow, 9th U. S. National Combustion Meeting, Cincinnati, OH, USA, 17-20 May 2015.
  4. Y. Minamoto and J. H. Chen, Direct numerical simulation of a turbulent lifted DME jet flame in a heated coflow at elevated pressure, 15th International Conference on Numerical Combustion, Avignon, France, 19-22 Apr. 2015.
  5. Y. Minamoto and N. Swaminathan, Sub-grid scale modelling for MILDcombustion, 35th International Symposium on Combustion, San Francisco, USA, 3-8 Aug, 2014.
  6. Y. Minamoto and N. Swaminathan, Scalar gradient behaviour in MILD combustion, 24th International Colloquium on the Dynamics of Explosions and Reactive Systems, Taipei, Taiwan, 28th Jul--2nd Aug, 2013.
  7. Y. Minamoto and N. Swaminathan, DNS of Turbulent MILD combustion, Proc. JSME-CMD International Computational Symposium, Kobe, Japan. 9-11th Oct., 2012.
  8. Y. Minamoto, T. D. Dunstan, N. Swaminathan and R. S. Cant, DNS of EGR-type turbulent flame in MILD condition, 34th International Symposium on Combustion, Warsaw, Poland, 29 Jul--3 Aug, 2012.
  9. Y. Minamoto, T. D. Dunstan and N. Swaminathan, DNS of EGR-type combustion in MILD condition, Proceedings of 7th Mediterranean Combustion Symposium, Sardinia, Italy. 11-15 September, 2011.
  10. T. Kadowaki, Y. Minamoto, N. Fukushima, M. Shimura, N. Swaminathan, M. Tanahashi, T. Miyauchi. Effects of Flow Geometry and Damkohler Number on Turbulent Premixed Flame, Proceedings of the Third Asian Symposium on Computational Heat Transfer and Fluid Flow, Paper ID: #174, p10, September 2011.
  11. Y. Minamoto, N. Fukushima, M. Tanahashi, T. Miyauchi, N. Swaminathan and D. Dunstan, Effect of flow-geometry and Damkohler number on turbulence-flame interaction, Proc. Fifth European Combustion Meeting, pp. 6, Cardiff, UK, 28 June-1 July, 2011.
  12. Y. Minamoto, Y. Nada, M. Shimura, N. Fukushima, Y.-S. Shim, M. Tanahashi and T. Miyauchi, Flow-Geometry and Reynolds-Number Effects on Flame-Turbulence Interactions, 8th ASME-JSME Thermal Engineering Joint Conference, Proc. 8th ASME-JSME Thermal Engineering Joint Conference, AJTEC2011-44472, March 2011.
  13. Y. Minamoto, Y. Nada, M. Tanahashi and T. Miyauchi, Principal Strain Rates at Flame Front of Three-Dimensional Turbulent Premixed Flames, Proceedings of 22nd International Colloquium on the Dynamics of Explosions and Reactive Systems, CD-ROM, Minsk, Belarus. 27-31. July, 2009.
  14. Y. Minamoto, S. Taka, M. Shimura, M. Tanahashi and T. Miyauchi, Simultaneous CH DPPLIF/OH PLIF and Stereoscopic PIV for Local Burning Velocity Measurements in Turbulent Premixed Flame, Proceedings of the 7th JSME-KSME Thermal and Fluids Engineering Conference, CD-ROM. Hokkaido, Japan 13-16 October, 2008.
  15. M. Tanahashi, S. Taka, T. Hirayama, Y. Minamoto and T. Miyauchi, Local Burning Velocity Measurements in Turbulent Jet Premixed Flame by Simultaneous CH DPPLIF/OH PLIF and Stereoscopic PIV, Proceedings of 14th International Symposium on Applications of Laser Techniques to Fluid Mechanics, CD-ROM, Lisbon, Portugal, 7-10, July, 2008.

日本国内学会

  1. 源 勇気, 青木 虹造, 店橋 護, Nedunchezhian Swaminathan, スワール予混合火炎における乱流混合の影響, 第28回計算力学講演会, No. 244, 神奈川, 2015年10月10日-12日.
  2. 源 勇気, Hemanth Kolla, Ray W. Grout, Andrea Gruber, Jacqueline H. Chen, 乱流JICF内浮き上がり火炎安定性に対する選択拡散の影響, 第53回燃焼シンポジウム講演論文集, 111f, 茨城, 2015年11月16日-18日.
  3. 源 勇気, 店橋 護、火炎干渉に関する数値的研究、日本機械学会 関東支部第22期総会講演会 講演論文集, GS0604, 東京都, 2016年3月10日‐3月11日.
  4. 源 勇気, 名田 譲, 店橋 護, 宮内 敏雄, 水素・空気乱流予混合火炎における火炎近傍の歪み速度特性, 熱工学コンファレンス2009講演論文集, 11-12, 山口, 11月7日-8日, 2009.
  5. 源 勇気, 名田 譲, 店橋 護, 宮内 敏雄, V型水素・空気乱流予混合火炎におけるひずみ速度特性, 日本流体力学会 年会2009講演論文集, CD-ROM, 東京, 9月2日-4日, 2009.
  6. 源 勇気, 高 翔平, 志村 祐康, 店橋 護, 宮内 敏雄, 乱流予混合火炎における局所燃焼速度の直接計測, 第45回日本伝熱シンポジウム講演論文集(1), 235-236, 茨城, 5月21日-23日, 2008.