Flow and Heat Transfer Due to a Buoyant Ceiling Jet Turning Downward at a Corner.
Flow and Heat Transfer Due to a Buoyant Ceiling Jet
Turning Downward at a Corner.
Kapoor, K.; Jaluria, Y.
Journal of Heat Transfer, Vol. 118, No. 1, 38-46,
Sponsor:National Institute of Standards and Technology,
corners; heat transfer; ceiling jets; buoyant flow
An experimental investigation has been carried out on
the flow and heat transfer characteristics of a
horizontal buoyant ceiling jet that turns downward at a
corner to yield a vertical negatively buoyant wall flow.
Such flow situations are frequently encountered in
thermal energy storage, in electronic systems, and in
room fires. However, not much work has been done to
understand the basic mechanics governing such flows,
particularly the flow near the corner. In this study, a
two-dimensional jet of heated air is discharged adjacent
to the lower surface of an isothermal horizontal plate.
An isothermal vertical plate is attached at the other
end of the horizontal surface, making a right angle
corner. The vertical penetration distance of the
resulting downward flow is measured and is related to
the inflow conditions, particularly to the temperature
and velocity at the jet discharge. This penetration
distance is found to increase as the distance between
the discharge location and the corner is reduced and
also as the relative buoyancy level in the inlet flow is
decreased. Velocity and temperature measurements are
also carried out over the flow region. These indicate
that the ceiling flow separates from the horizontal
surface just before reaching the corner and then
reattaches itself to the vertical wall at a finite
distance vertically below the corner. The local surface
heat flux measurements show a minimum in the heat
transfer rate before the turn, along with a recovery in
the heat transfer rate after the turn and the existence
of a small recirculation zone near the corner. The net
entrainment into the flow and heat transfer rate to the
solid boundaries are also measured and correlated with
the jet discharge conditions.