抄録
The periodic oscillation of diffusion flame,
known as (bulk) flame flickering, is a well-known
dynamic behavior connected with flow-associated
instabilities triggered by gravity-induced buoyant
flow. In this study, the flickering behavior of a wick
assisted flame was experimentally examined under
partial gravity fields ranging from 1 G to 0.075 G,
where G is the normal gravity acceleration (9.81
m/s2). The subjected gravity was controlled using
the “Slope-Sliding-Method environment 2,” which
allows repeatable and finely adjustable gravitational
conditions in laboratory experiments. Temporal
variations in flame height were recorded and
analyzed using fast Fourier transform to extract
characteristic frequencies. The specific objectives of this work are (1) to determine the gravity dependence
on flickering frequency and (2) to observe the “critical” gravity, where flickering is suppressed under a
substantially reduced gravity regime. The results indicate that the well-known Strouhal–Froude number
correlation is preserved down to ~0.17 G, while distinctively different flickering behavior occurs below
this point owing to a different mode of periodic oscillation. Theoretical analysis indicates that the
characteristic delay time by the conductive heat transfer in the present wick-assisted flame system plays a
role under such highly reduced gravity conditions. Although special care must be taken to investigate the
“critical” gravity, this work is the first to reveal that weak flickering is preserved, even under a Lunar or
Martian gravity environment.
