الفهرس 
EXPERIMENTAL WORKOnly 14 pages are availabe for public view
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Abstract
Impinging jets are an established technique for obtaining high local
transfer coefficients between a fluid and a surface. They are employed
in different ranges of heat and/or mass transfer applications including;
heating or cooling of large surface area products, drying of paper and
textiles, cooling of gas turbine blades and annealing of metals and
plastic sheets.
A significant amount of research has been conducted on the problem
of cooling a uniform heat flux surface, with gas or liquid jets.
However, there have been very few attempts to study the problem of
heating a flat plate normal to the jet axis. The only experimental
research, up to my knowledge, that studies heating an inclined flat
plate using hot air jets has been carried out in 1952. Nevertheless this
research has been criticised by other researchers.
In the present study an experimental investigation is conducted on the
local heat transfer coefficients for a round jet of hot air, issuing from a
27 mm diameter tube, striking an oblique solid surface. The problem
parameters investigated are the plate inclination, the nozzle-to-plate
spacing and the jet Reynolds number. It is found that the point of
maximum heat transfer is displaced uphill from the geometric
impingement point and the magnitude of this displacement increases as
the plate inclination increases. The local coefficients on the uphill side
of the point of maximum heat transfer tend to DROP off more rapidly,
unlike those on the downhill side. Thus, on comparing oblique
impingement to normal impingement, there is an unsymmetric
distribution in the local heat transfer coefficients about the stagnation point, this asymmetry increases as the plate inclination increases.
Moreover, inclined jets provide higher heat transfer coefficients on the
downhill side and lower heat transfer coefficients on the uphill side,
leading to imbalance in the heating capabilities on the two sides. It is
also observed that the stagnation point Nusselt number decreases as
the plate inclination increases. An empirical correlation of the
experimental data along the plane of the plate inclination is developed.