Response of spherical diffusion flames under rotation with general Lewis numbers

The structure and extinction of diffusion flames generated by a porous spherical burner or a fuel droplet in response to rotational motion were investigated through perturbation analysis, with emphasis on the effects of non-unity Lewis numbers (Le) for both fuel and oxidizer. The analysis shows that the rotational motion induces a secondary flow that distorts the otherwise spherical flame into a pancake shape. The flame temperature is also affected, such that the flame becomes more susceptible to extinction either at the poles or the equator, depending on the combined effects of Lewis numbers, flame stretch through local flow non-uniformity and ambient oxidizer concentration. The results reported here will help guide planned microgravity experiments.

Acknowledgement

This work was supported by the microgravity combustion program and GSRP of NASA.