Abstract
In this paper, an experimental investigation was conducted to analyze the effect of spacing between vertical plates of
a parallelepipedic canal on the average thermal and dynamic fields of a thermal plume. To carry out this study, we
placed at the laboratory a rectangular heat block at the entry of a vertical canal open at the ends. The internal walls of
the plates are heated uniformly by Joule effect and by thermal radiation emitted by active source. The heating of
walls creates a thermosiphon flow which interacts with the plume inside canal. Four dimensionless spacing between
the plates 1.25 ≤ e* ≤ 30 are considered. It is found that the spacing is the most important geometrical parameter
affecting the thermal and dynamical behavior of the flow. Using visualization by laser plan and hot wire probe, flow
structure evolves in two zones for smallest and largest spacing while a supplementary zone near heat source is
observed for an intermediate spacing. The variation of flow rate and energy transported by the fluid shows the
existence of an optimum spacing where the propagation of plume flow is more accelerated.