Two-Droplet Combustion of N-Octane in a Direct Current Electric Field Under Microgravity

Abstract

The combustion experiments of two droplets of n-octane arrayed in the direction of the electric field were carried out under microgravity. Experiments with different electrode distances are carried out and two individual flames were observed. The increase in the burning rate constant of the cathode-side flame was arranged reasonably using the representative electric body force, which was expressed by the product of the square of the applied voltage and the inverse cubic electrode distance from the one-dimensional steady-state analysis. The increase in the burning rate constants is discussed by the convection effect and the experimental results are estimated in an analogy of the effect of Grashof number on droplet combustion. For the anode-side flame, a luminous flame at the positive-side end that emits negatively charged soot particles is observed, which induces the local flow in an antiflow direction, preventing convective heat transfer to the droplet.

Keywords:

• DC electric field
• Electric body force
• Microgravity
• Separated flames
• Two-droplet combustion

ACKNOWLEDGMENTS

Authors are grateful to Mr. M. Utsumi, Mr. T. Iwata, Mr. Y. Kubo, Mr. I. Kume, and Mr. M. Kakinoki for their assistance during the experiments.