Modern combustion engines produce a great deal of heat while
producing power. To avoid damage due to overheating, the radiator
is used to transfer the heat from the metal block and heads
to a mixture of antifreeze and water, and out to air moving
through the radiator. Effective heat control, then, relies heavily
on efficient and consistent flow of cooler air through the radiator.
The MINI’s distinctive front end has two opening in front
of the radiator, one low in the bumper and one at the front
of the clamshell bonnet. Though this would seem to be advantageous
for more airflow, the design leaves much room for improvement.
The openings are separated in the fascia by a solid bumper that
blocks a significant portion of the radiator’s cooling
surface from fast moving, direct airflow. In this case, to move
air through the blocked portion of the radiator, the design
relies on a pressurization of the open area between the bumper
and the radiator. Since the area behind the radiator is at a
lower pressure, this works in theory. Unfortunately, the theory
is not always a reality.
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 At
the top of the bumper on the MINI, there is an open gap
between the lower grille inlet and the upper grille inlet.
This area allows air to pass freely between the two openings.
This could allow the open area to act as one single pressurized
region to force air to flow through the radiator, but
in truth it is more inefficient in regards to cooling.
In the lower section there is a second heat exchanger
for the air conditioning (the smaller of the two radiators).
To cool correctly, the air must pass through both, but
the longer flow path presents a larger resistance to flow
than the section of the radiator not covered by the AC
heat exchanger (the part above the bumper line). Since
air will follow the path of least resistance, the design
leads to an interesting effect that can be seen in the
following fluid flow analysis diagrams. |
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 The
first Computational Fluid Dynamic (CFD) simulation was run as the stock setup, with the
area above the smaller radiator open. Upon a quick inspection
of the results, several oddities should become readily
clear. The first is that there is a section of the radiator
where there is no flow (arrow 1)! The air that should
flow through that part of the radiator (arrow 2) is following
the path of least resistance, flowing up and over the
double thick region and through the single region above
leaving significant portion of the radiator with no cooling
air flowing through it. This will reduce the efficiency
of the radiator.
Always thinking, M7 has developed the Air Plate Diverter
(APD) to help stop the migration of the cooling air from
the lower grille to the upper section of the radiator
where it is not needed. The APD separates the two open
areas behind the bumper and bonnet, trapping the air.
As the CFD simulation shows, with the APD installed, the pressure
buildup in the lower opening will force the air to move
through the entire double-thick radiator system. There
are no more dead spots as there is no longer a path of
less resistance for the air to take. |
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