|
A schematic of the problem is shown in Fig.1. A planar jet is
impinging against a plate of length 2L and kept at the constant
temperature Tw. The jet is emitted from rectangular
nozzle with the width 2d = 1.29e-3 m and length
l=7.62e-2 m. The nozzle's outlet is located h =
6.35e-3 m above the plate. At the inlet of the nozzle, a uniform
velocity profile, U0 and constant temperature,
T0, are specified. Considering the symmetry of the
problem the computational domain shown in Fig.1 includes only a
half of the physical domain. The flow was computed using Coolit
CFD software, which solves the Navier-Stokes or the Reynolds
averaged Navier-Stokes equations depending on whether laminar or
turbulent flow was considered. For turbulent jets, we used the
eddy viscosity turbulence model without wall functions [1]
offered by Coolit. The computed results were compared with
impinging jets experiment by Gardon and Akfirat [2].
A comparison of computed and experimentally measured heat flux
along the plate at two values of Reynolds numbers was carried out.
The Reynolds number was based on the velocity at the nozzle inlet
and nozzle width, Re= U02d/n, is presented in Fig.2. In the laminar
flow regime, Re=450, the agreement of the predicted and measured
heat flux values is virtually ideal. For the turbulent flow, Re=2750,
there is a local discrepancy in the vicinity of the region where
the transition to turbulence most likely occured. The exact
transition point cannot be predicted by any of the existing
turbulence models and such behavior is expected. The key
parameters in practical simulations, however, is not the point
distribution of the heat flux but the integral heat flux, for which the
model provided an excellent agreement.
References:
[1] M. Strelets, M. Shur, L. Zaikov, A. Gulyaev, V. Kozlov,
and A. Secundov, "Comparative Numerical Testing of One- and
Tow-Equation Turbulence Models for Flow with Separation and
reattachment", AIAA Paper, 95-0863.
[2] R Gardon, J. C. Akfirat, "Heat Transfer Characteristics of
Impinging Two-Dimensional Air Jets," Journal of Heat Transfer,
ASME, Series C, vol. 86, pp. 101-108, 1966.
|
