Effects of Turbulence Characteristics in the Spray Combustion

Abstract

The present study was conducted in order to clarify the effects of airflow turbulence on the spray combustion. Methanol was atomized with the two-fluid-type nozzle in order to generate the spray flame, and the turbulence characteristic of the flame was varied by inserting a mesh near the tip of the nozzle. Droplets in the spray flame were measured using a PDPA system in a reaction field, and changes in the turbulence characteristic were measured using a hot-wire anemometer in a no-reaction field in order to clarify the effects of turbulence on combustion behavior. Inserting a finer mesh promoted droplet evaporation and enhanced the dispersion characteristic. Regarding changes in the turbulence characteristic, the integral time scale increased and the energy spectrum decreased as the inserted mesh became finer. Based on the obtained results, we determined that a finer mesh causes vortexes to be more persistent and enhances the dispersion characteristic of the droplets.

Influences of Turbulence Characteristic on the Dispersion Behavior of Droplets in the Spray Flame

“…At any position, the value became greater as the wire mesh became finer. These results were the same tendencies shown by the former report (3) .…”

“…So, in the method which is the same as the former report (3) , the turbulence characteristics of the air current as the base flow in a no-combustion field without fuel atomization were measured by a hot wire anemometer. Figure 8 shows the calculation results.…”

“…As introduced in the previous report (3) , wire meshes of different mesh sizes were inserted behind the two-fluid type nozzle to vary the turbulence characteristics of the air current, and then methanol was sprayed to form a spray flame, as shown in Fig.1.…”