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Show A recent development by D a h m 6 (1997) at the University of Michigan has further modified the characteristic length, to account for the combustion reaction. In short, the density of the surrounding fluid, p-is modified to an effective density, (p-W-The new effective density is a function of the jet and surrounding temperatures, and the jet mixture fraction. The approach agrees favorably with available data. A summation of Dahm's efforts about the temperature uniformity problems in practical combustion applications. 4.0 Test Equipment Three lab experiments were conducted to investigate high velocity burner performance. Several brick kilns were also used as field test sites. The first lab experiment involved firing a modified burner into a small, empty furnace (116 ft3) that was fitted with seven thermocouples parallel 150 200 250 X/d0 Figure 3 Variation of Entrainment Rate with Density (Ricou & Spalding, 1961) effect of reacting jets on mixing entrainment is provided as follows: and 1. Heat release effects appear to extend the potential core 2 to 3 times. 2. Equivalence ratio and flame temperature effect the mixing between the jet and surrounding fluid. Leaner and cooler flames increase the rate of mixing. 3. Heat release effects appear to slightly reduce the rate of mixing of the jet and surrounding fluid. The principles of jet theory and efforts of prior investigators help to better understand the mechanisms of heat uniformity, and more importantly, how to resolve to the flame jet. Temperature uniformity of the seven thermocouples was then compared between tests. Three effects were evaluated in this experiment: recessing the burner in the furnace wall, firing burners with non-circular shaped nozzles, and firing burners with smaller nozzle areas (i.e. increasing the velocity of the jet). Combinations of the above were also investigated. The next series of lab experiments dealt with measuring and comparing entrainment of round versus rectangular (slotted) nozzles. Figure 4 shows a high velocity burner fired downward into a cylindrical chamber. All testing was conducted in ambient air. Chamber pressures and 4 |