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Turbulent Forced Convection Augmentation by Flow Destabilization

IP.com Disclosure Number: IPCOM000122073D
Original Publication Date: 1991-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 50K

Publishing Venue

IBM

Related People

Agonafer, D: AUTHOR [+3]

Abstract

Conventional turbulators or eddy promoters utilize flow disturbance devices which result in separation and subsequent attachment of boundary layers resulting in initiation of high gradients and corresponding heat transfer augmentation. For example, off-set strip fins utilize this concept by interrupting the flow and reinitiating an inlet flow with high gradients. It is to be observed that most of these techniques utilize eddy promoters with geometries of the same order as the dimension of the channel. However, for turbulent flow, the biggest resistance to heat transfer is in the viscous (laminar) sub-layer.

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Turbulent Forced Convection Augmentation by Flow Destabilization

      Conventional turbulators or eddy promoters utilize flow
disturbance devices which result in separation and subsequent
attachment of boundary layers resulting in initiation of high
gradients and corresponding heat transfer augmentation.  For example,
off-set strip fins utilize this concept by interrupting the flow and
reinitiating an inlet flow with high gradients.  It is to be observed
that most of these techniques utilize eddy promoters with geometries
of the same order as the dimension of the channel.  However, for
turbulent flow, the biggest resistance to heat transfer is in the
viscous (laminar) sub-layer.  Introduction of disturbances in the
viscous sub-layer in the form of microcylinders or microgrooves in
the order of the size of the boundary layer will create hydrodynamic
instabilities in the laminar sub-layer (which represents the region
of highest resistance to heat flow).  Furthermore, these disturbances
are continuous and will, therefore, result in a continuous breaking
up of the boundary layer and a corresponding heat transfer
enhancement.

      The figure shows two substrates 1 populated with chips 2 facing
each other with fluid flowing between the substrates.  Heat transfer
augmentation is made possible by introducing microcylinders 3 in the
form of fairly inexpensive small wires on the chips.  The wires can
be held in place with EC pads.  Alternatively, microgrooves 4 can...