| Summary: | The problem of multiple turbulent jet interactions is investigated with special attention
to applications in kraft recovery boilers. The phenomena due to turbulence are simulated
with the k-ε turbulence model, and a multigrid numerical technique is applied to solve
the time-averaged Navier-Stokes equations governing the flows. Investigations carried out
include a study on the simulation of primary level jets and on the characteristics of a row
of jets discharging into a confined crossflow. For the primary level jets, the interaction
and merging of the jets are investigated. The jets merge rapidly and a suitable open
slot representation gives an adequate description of the velocity field. For jets in a
row interacting with a confined crossflow, the effects of varying the jet spacing on flow
characteristics are investigated. At moderate spacing, the penetration decreases as the
spacing is reduced. It is also observed that the vorticity structures of a jet within the row
can be substantially different from those of an isolated jet. The penetration of rectangular
jets from orifices having different aspect ratios is then studied. A quantitative analysis
is carried out to examine the extent of mixing between the jets and the crossflow. The
applicability of a correlation by Holdeman and his co-workers is extended to rectangular
jets. The correlation yields information on the penetration at various values of jet spacing,
confinement size, and jet-to-crossflow momentum ratio. Holdeman’s correlation is also
found to be applicable to a crossflow having a peaked non-uniformity in the velocity
profile. The use of Holdeman’s correlation indicates that, for a given mass flow from
the jets, large jets at a low momentum can penetrate as far as smaller jets at a higher
momentum. Furthermore, because of their low momentum, these large jets introduce a
lower degree of flow non-uniformity in the mainstream.
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