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1993 Fiscal Year Final Research Report Summary

CFD Simulation of Turbulent Combustion for Description of Non-Uniform Process by a Stochastic Approach

Research Project

Project/Area Number 04650187
Research Category

Grant-in-Aid for General Scientific Research (C)

Allocation TypeSingle-year Grants
Research Field Thermal engineering
Research InstitutionKYOTO UNIVERSITY

Principal Investigator

SHIOJI Masahiro  Kyoto Univ., Mech.Engr., Assoc.Professor, 工学部, 助教授 (80135524)

Co-Investigator(Kenkyū-buntansha) YAMANE Koji  Kyoto Univ., Mech.Engr., Instructor, 工学部, 助手 (10210501)
IKEGAMI Makoto  Kyoto Univ., Mech.Engr., Professor, 工学部, 教授 (70025914)
Project Period (FY) 1992 – 1993
KeywordsTurbulent Diffusion Flame / CFD Simulation / Concentration Heterogeneity / Stochastic Model / Engine Combustion / NOx Concentration / Lean Burning
Research Abstract

A stochastic approach was applied to computational fluid dynamic (CFD) simulation to establish efficient program valid for predicting turbulent combustion. The program placed a special emphasis on description of concentration and density fluctuations due to local heat release which are essential to the pollutant formation in highly turbulent combustion, such as an engine combustion. Obtained results in the present study are summarized as follows.
(1)The probability density function (pdf) of the mass fraction of fuel was taken into consideration in each computational cell of a finite difference CFD program to allow description of the microscopic heterogeneity of mixture concentration. Changes of pdf due to convection and diffusion were solved using hybrid scheme in an implicit method. Furthermore, the process of turbulent mixing was expressed by a collision-redispersion model. The collision rate was estimated from the turbulence characteristics based on the k-epsilon model.
(2)The accurac … More y of the above prediction program was investigated for a simple case of one- and two-dimensional turbulent flows. It was shown that the time evolution of the mean concentration was consistent with theoretical one as long as twenty or more fluid elements in each cell are chosen. In addition, the simulation program for a more practical in-cylinder flow was performed for a further test.
(3)To investigate the effect of mixture heterogeneity on the formation of oxides of nitrogen in the engine combustion, the histories of temperature distribution and NO concentration were calculated using a thermodynamic model based on the measured rates of heat release for the mixture condition having different degrees of heterogeneity. It was shown that a higher NO concentration originates from the hot burnt gas initially ignited. Thus, a lean burning of spark-ignition engines with a more homogeneous mixture should be used for NOx reduction. It was also suggested that much reduction of NO may be achieved once the burnt gas is made stirred. Less

  • Research Products

    (2 results)

All Other

All Publications (2 results)

  • [Publications] 塩路昌宏: "希薄燃焼内燃機関の窒素酸化物生成に及ぼす混合気濃度不均一の影響" 日本機械学会講演論文集(関西支部第69期定時総会講演会). No.944-2. 283-285 (1994)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] M.Shioji: "Effect of Mixture Heterogeneity on the Formation of Oxides of Nitrogen in Lean-Burn Internal Combustion Engines" Proc.JSME Meeting (Kansai Branch). No.944-2. 283-285 (1994)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 1995-03-27  

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