| Summary: | 碩士 === 中正理工學院 === 兵器工程研究所 === 86 === ABSTRACT
The objective of the present investigation is to explore
the influences of g-jitter effect on threshold of thermal
instability and natural convection flow structure and heat
transfer. By invoking Boussinesq approximation , the
governing equations are cast into a form of
velocity-vorticity formulation , and then solved on a
uniform staggered grid by a numerical procedure based on
central difference scheme. The physical model considered
is air of Pr=0.71 in a rectangular enclosure of
width-to-length aspect ratio 4:1. The enclosure is heated
from below and of two side-walls insulated.Firstly,thermal
instability in horizontal enclosure with g-jitter of
various amplitudes and frequencies is investigated. In the
second part , the gravity modulation effects on flow
structure and heat transfer performance are studied. The
results show that the g-jitter effects delay the onset of
thermal instability and the effect is maximun at the high
amplitude and middle frequency. The results also reveal
that the thermo-flow characteristics can be strongly
influenced by the g-jitter effects especially that of low
frequency and large amplitude.
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