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Show regardless of real Re number in the fully turbulent field. This means that the flow pattern of the turbulent field is not changed significantly even if the real Reynolds number 1s changed. Sato9) compared the flow pattern in the gas turbine of different scale by using a cotton streamer and showed that the flow pattern 1s nearly the same in api te of the increase of Reynolds number by double. We found from a experiment that the analogy of flow pattern is attained when the Reynolds number of free jet is held over 4xl04 in the case of free jet .10) From these discussions, it is indicated that the real Reynolds number does not influence significantly the means flow pattern when an analogy of the geometrical configuration such as the ratio of burner nozzle diameter to the combustor diameter is maintained. However, analogy of the geometrical configuration becomes difficult in the case of a large scale charge. For example, this is easily understood when one considers that in the case of scale down by 1/100, burner diameter of lOem of prototype becomes lmm in the model. When an analogy of the geometrical configuration can not be maintained, some similitude parameters which can coincide macro flow pattern were prepared for some typical flows. These are for example, Curtet-Craya number in the confined jet, Swirl number in the swirling flow, Patrick number in the cross jet .11 ) In general, as analogy between momentum, heat and mass transfer can be held mostly in the turbulent field , an analogy of the distribution of local air ratio can be maintained when the flow pattern is coincided between a model and a prototype. 4. Scale effect on mixing characteristics Amongst the basic factors which influences the pollutant formation, the macro and micro mixing time are influenced significantly by the scale change. Here, the Bcale effect on the micro mixing time is discussed at first. According to Corrs1n12 ), the micro mixing time 't II in the isotropiC turbulent field of gas-gas mixing can be given by the 4 |
