Normally-Impinging Jet from a Circular Nozzle
Experiments by Cooper et al., and Baughn et al.
The experiments provide an extensive set of measurements of a turbulent
jet impinging orthogonally onto a large plane surface. Two Reynolds numbers
have been considered, 2.3 × 104 and 7 × l04,
while the height of the jet discharge above the plate ranges from two to ten
diameters, with particular attention focused on two and six diameters. The
experiment for the velocity field was designed so that it provided
hydrodynamic data for conditions the same as those employed by
Baughn & Shimizu when measuring heat-transfer rates. Before
discharge, the air passed along a smooth pipe sufficiently long to give
fully developed flow at the exit plane of the jet: a feature that is
helpful in using the data for turbulence-model evaluation. Hot-wire
measurements have been made with inlet pipes of nominally one-inch (26 mm) and
four inches (101.6 mm) diameter. Data are available of the mean velocity
profile in the vicinity of the plate surface and also of the three
Reynolds-stress components lying in the x-r plane. Computational
results reported in Ref.  indicate a good degree of internal consistency
between the mean and turbulent field data in that models predicting the mean
flow poorly (or well) also predict the turbulence data poorly (well).
Inlet and Boundary Conditions
As noted above, at the pipe exit, the flow should be fully-developed.
In computational work, it is suggested that an initial calculation
should be done to generate fully-developed pipe flow profiles at
the apprpriate Reynolds number, which can then be used as inlet
conditions for the impinging jet computation.
The outlet plane should be placed at a sufficiently large
radial distance that errors arising from the application
of zero-gradient (or similar) conditions will not significantly
affect the region of interest. For the present measurements
(extending to around r/D=6), it is suggested that the
outer radial boundary should be at r/D=8 or greater.
The boundary opposite the impingement wall is a surface
across which fluid in entrained. One common method of dealing
with such boundaries (in pressure-correction based finite-volume
solvers) is to impose ambient pressure values at the boundary, and
to allow fluid to be entrained at the rate necessary to satisfy
continuity in the boundary cells.
Reference and Previous Solutions
References and Related Publications