Jun Osaka

Observation of sooting behavior in single droplets combustion in direct current electric fields under microgravity

Because of ions and electrons in flame, flow is induced around flame in electric filed. It affects combustion phenomena, and the effect has seemed to be significant for droplet combustion in previous study. This study is focused on movement of soot particle in single droplets combustion in direct current electric fields under microgravity in order to obtain some information about flow field around droplet. The large soot particles were observed by high-speed CCD camera, and the soot velocities are measured by PTV method. The single droplets were burned in the center of electrodes, which are two parallel rectangular wire nettings. Distance between electrodes is 50mm and applied voltages between electrodes are from 0kV to 6kV. Fuels tested are n-octane and toluene and the initial droplet diameters are around 0.8mm. All experiments were performed in microgravity in order to eliminate the natural convection. The results shows the velocities of soot particle are mainly in the direction of electric field, and most soot particles move to the cathode but some move to the anode. This indicates some soot particles have some negative charges. The velocities of soot particle increase with increasing in the distance from the droplet in both directions, and the velocity to cathode is larger than that to anode. From these results, the change of electric field and flow field around droplet are discussed.

Sooting Flame Behavior for a Droplet Combustion with Electrical Field under Microgravity

The sooting droplet combustion behavior under electrical fields is investigated with n octane fuel. The numerical simulation which includes the combustion gas, liquid fuel and soot particle is carried out and compared with experimental results obtained in the microgravity environmental. Flame de formation and burning rate constant are predicted and enhancement of evaporation is shown. The mechanism that n -octane sooting flame under electrical fields is evaporated than none electrical fields case is considered.

Effects of Direct Current Electric Field on Separated Flames in Two Droplets Combustion under Microgravity

This paper shows the results of n-octane two droplets combustion in DC electric field following our previous study. Fiber-supported two droplets are burned under microgravity in air at atmosphere pressure and room temperature. Droplets are arrayed in the directions of electric field with 10 mm distance between droplets and in this condition both flames are individual and have very little interaction between them without an electric field. The equivalent applied elctric field is around 0 to 120 kV/m. The results show that flames are principally deformed to cathode with electric field, however, luminous flame at anode-side end is observed for anode-side flame while blue flame is observed at anode-side end of cathode-side flame. In addition, the increase in burning rate constants for both flames are observed and the increase in burning rate constant for cathode-side flame is larger than that for anode-side flame. The increase in burning rate constant is consistent to information from flame intensities. For cathode-side flame, an analogy to droplet combustion in force convection is discussed in terms of flame deformation and burning rate constants and a relation between them shows good agreement to that under forced convection quantitatively. The increase for anode-side flame is also mentioned from flame deformations.