| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1991: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1990: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Research Abstract |
Turbulence can increase the burning velocity of premixed mixture, it can extinguish the flame, either. The effects of turbulence on the turbulent combustion process in internal combustion engines depend on the complicated interaction of the turbulent mixing with the chemical reaction therein. Therefore, to clarify the relation of the local flame quenching with the fine flame structure, it is necessary to investigate how they are affected by the turbulent mixing and chemical reaction. This has been done experimentally and theoretically in this study.
In the experimental study, the schlieren photography and laser-sheet tomography were used to visualize the fine structure of the flame, and passive electrostatic probes to detect the flamelets from the flame zone. By the experimental work, the curvature of the flamelets and its variation with independently controlled combustion was visualized and the flamelet number in the flame zone measured from 1 to 6, increasing with the ratio of the tur
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bulence intensity to the laminar burning velocity. The islandlike feature of the flamelets in the zone was suggested by schlieren photographs of the flame and supported by the multi-flamelet fact revealed by the passive electrostatric probe method, but has not yet observed by the laser-sheet tomography probably owing to the deficient contrast of the tomograms. The conditions for flame quenching have also been determined experimentally for several mixtures with relatively low laminar burning velocities.
In the theoretical study, such a model has been developed which describes the premixed combustion from laminar to turbulent flames, and provides parameters for the flame structure as well as the turbulent burning velocity. In order to clarify the relationship between the flame structure and turbulent burning velocity, three coordinate systems (Re-Da, eta_K/eta_0-u'/S_<L0>, L/eta_0-u'/S_<L0>) SO far used for the flame structure phase-dia, , rams individually, were shown to be related to one another and used to present the model-predicted burning velocities and flame structure parameters in the form of diagrams. Less
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