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2001 Fiscal Year Final Research Report Summary

Study on the Atomization Gasification, Mixing and Combustuin Processes of Liquid fuel Jets in Supercritical Enironments

Research Project

Project/Area Number 11650219
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Thermal engineering
Research InstitutionNagoya University

Principal Investigator

UMEMURA Akira  Nagoya University Department of Aerspace Engineering, Professor, 工学研究科, 教授 (60134152)

Project Period (FY) 1999 – 2001
KeywordsSupercritical Ambience / Spray Combustion / Atomization Mechanism / Ignition Delay Time Vortex Burstion / Vortex Burstion / Critical Mixing Surface / Turbulence / Hydrodynamic Action
Research Abstract

Analyzes were made of characteristic processes involved in the combustion of sprays which are formed when liquid fuel is injected into the air whose thermodynamic state exceeds the critical point of the fuel. The following were found. ( 1) Despite the convectional belief that droplet auto-ignition delay time shortens monotonically with increasing pressure, it was found that the droplet auto-ignition delay time takes a peak at the ambient states near to the fuel critical point. This secular behavior is due to the influence of the phase equilibrium condition at droplet surface. Considering that current diesel engines operate at such condition, this knowledge addresses an interesting problem of finding an optimum spray condition for fast combustion. (2) Atomization is a keytechnology to spray combustion. However, the understanding of atomization mechanism involved in high-pressure sprays used in liquid rocket engines and diesel engines are very poor because optical observation is very difficult at high pressures. The current concept is based on the knowledge obtained from the experiments of water jet atomization at standard pressure. We examined the instability of jets with near-critical mixing surface and found a new instability mode with growth rate proportional to jet speed, which can make the liquid jetbroken into droplets with short spacing with the aids of hydrodynamic action. This finding theoretically bases the formation of dense sprays constituting of fine droplets at high pressures, if we regard a low-speed liquid jet as one of the liquid ligaments formed in the turbulent atomization process of an injected liquid. Furthermore, we studies (3) the mechanism of rapid flame propagation through combustible vortices formed in the process of turbulent mixing and (4) the modes of flame spreading between droplets for a various kind of sprays.

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] 梅村章, 富田浩一: "可燃性混合気渦の中を伝わる火炎の数理的研究 (第1報:新しい高速火炎伝播機構の提案)"日本機械学会論文集B編. 65. 3169-3176 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 梅村章, 富田浩一: "可燃性混合気渦の中を伝わる火炎の数理的研究 (第2報:数値的検証)"日本機械学会論文集B編. 65. 3177-3184 (1999)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Umemura, S.Takamori: "Wave Nature in Vortex Bursting Initiation"Proc. Combust. Inst.. 28. 1941-1948 (2000)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A.Umemura, K.Tomida: "Rapid Flame Propagation in a Vortex Tube in Perspective of Vortex Breakdown Phenomena"Combustion Flame. 125. 820-838 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 若嶋勇一郎, 菱田学, 梅村章: "微小重力場での近臨界表面液ジェットの不安定性 (第1報:実験結果)"日本機械学会論文集B編. (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 梅村章, 若嶋勇一郎: "微小重力場での近臨界表面液ジェットの不安定性 (第2報:理論的考察)"日本機械学会論文集B編. (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] A. Umemura & K. Tomida: "Mathematics and Physics of Flame Propagation in Combustible Vortices (First Report : Proposed New Mechanism of Rapid Flame Propagation)"Trans. JSME(B). 65. 3169-3176 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A. Umemura & K. Tomida: "Mathematics and Physics of Flame Propagation in Combustible Vortices (First Report : Numerical Validation)"Trance. JSME(B). 65. 3177-3184 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A. Umemura & S. Takamori: "Wave Nature in Vortex-Bursting Initiation"Proc. Combust. Inst.. 28. 1941-1948 (2000)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A. Umemura & K. Tomida: "Rapid Flame Propagation in a Vortex Tube in Perspective of Vortex B reakdown Phenomena Y. Wakashima, M. Hishida &A. Umemura / Instability of Near-Critical Mixing Surface Jet in Microgravity (First Report : Experimental Result)"Combust. Flame. 125. 820-838 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Y. Wakashima, M. Hishida & A. Umemura: "Instability of Near-Critical Mixing Surface Jet in Microgravity (First Report : Experimental Result)"Trans. JSME(B). (in print). (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] A. Umemura & Y. Wakashim: "nstability of Near-Critical Mixing Surface Jet in Microgravity (First Report : Theoretical Consideration)"Trans. JSME(B). (in print). (2002)

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

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Published: 2003-09-17  

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