Fundamental Study on The Mechanism of Turbulent Combusiton and Its Model

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When we think of the world wide energy issue and the persistence of desirable circumstances, it is necessary to establish the scientific procedure to promate both the effective utilization of energy and the reduction of pollutant emissions. The elucidation of turbulent combustion mechanism and the control of combustion are essential for the purpose. One of the main objects of the present study is to obtain knowledge related to flame structures varying with the combination of various steps of reaction and turbulence intensity and to understand the interaction between combustion reaction and turbulence. Another object is to propose a combustion model based on the experiments which can be applied for the control of combustion. The following conclusions are obtained.1) Flame structure of a turbulent flame changes from the structure of a srinkled laminar flame into that of a distributed reaction zone when the wquivalence ratioof the mixture is decreased in spite of a weak turbulence. Low Damkoler number flames fealized by shortened mixing characteristic time scale and by increased chemical characteristic time scale showed similar flame structure.2) The fundamental feature of the propased combustion model consists of chemistry- and mixing-controlled reaction rates which vary with the local Damkoler number. The smooth time-averaged temperature profile in a typical turbulent flame can be successfully predicted by the present nodel which is dependent on the distribution of local Damkoler numbers. Since the accuracy of the model is intimately related with the local Damkoler number, hence the turbulence length scale, discussion of turbulence model inflames beeds a future study.