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Show The previous work of Sroka and Forney suggested that the unmixedness. in a tee junction isothermal mixing, is described by the following equation in the near field from injected point and the jet mixing mechanism as discussed before. .l/=A|M"|-P (10) \D, (DJ , -____ (ID "' u, Here, lm is the jet momentum length or distance the jet penetrates into the pipe before it bends over in the cross flow '''. Sroka and Forney concluded that m = 2 and k=0.42 for the tee mixer. This theory can be also used in the near field of the multi-jet mixing. In general, the municipal waste incinerator does not have long mixing length because of space saving. Therefore this study applied the equation (10) to the model incinerator having four nozzles in order to generalize the relationship of Figure 5. Figure 6 shows the relationship of (lm/D)'- and M(x/D)"\ The jet mixing can be considered in the range of (lm/D)'- from 0.05 to 5. because the scattered plots are on the solid line. In the case that (lm/D) - is below 0.05, the mixing is caused by the jet impacting, where the unmixedness is fairly low compare to the jet mixing case. O n the other hand, above (lm/D)'-=5.0 the slope of plots is easier than that of the jet mixing. From this result, the multi-jet mixing in the model incinerator that is not isothermal flow can be generalized by equation (10). In this study, the coefficient in the equation is k=0.088 and m=3.5. 5.4 THE EFFECT OF DENSITY RATIO Density ratio of the primary flow to the jet flow depends on the operating conditions. Even though the velocity ratio of the primary flow to the jet flow is constant, the penetration of the jet could change if the density is different. Since, in general, the jet penetration into the cross flow is depend on the momentum ratio of main flow to jet flow, the other parameter considered is the density. Figure 7 shows the comparison of the unmixedness for the density ratio is 1.0 and 2.47. Although equation (1) can be applied to the case of rj/r0=1.0, the constant k is different. In order to evaluate the effect of the density ratio on unmixedness. flow simulation was conducted for various density ratio by changing temperature of the primary flow. Figure 8 shows the effect of the density ratio on the unmixedness. The unmixedness M is proportional to (r/r,,)1. From this relationship, equation (11) can be described following form including the effect of densitv. |