The passage of a fluid through
a porous medium typically results in the transfer of heat between the
fluid and the medium. If the porous medium contains more heat than the
fluid, it will be cooled by the transpiration of the fluid through the
porous structure. In some applications, this effect may be useful when
a particular component tends to overheat.
Dynapore® diffusion-bonded porous metal structures offer a matrix
with high internal surface area and controlled permeability to flow. If
a particular component is fabricated from a suitably selected Dynapore®
material, the component may become "self-cooling" in the context
of the application.
As an example, in liquid hydrogen/oxygen rocket engines, the hydrogen
fuel injector nozzles may be embedded in a flat solid plate. The nozzles
may have a tendency to overheat and melt. By substituting a high-strength
controlled permeability Dynapore® material for the solid plate, a
pre-determined percentage of the hydrogen may be permitted to flow through
the plate itself, with the balance flowing through the injector nozzles.
The plate is cooled by the transpiring flow of hydrogen through its internal
void volume. The cooled plate in turn becomes a heat sink and prevents
the nozzles from melting.
Other applications for transpiration-cooled components have included
combustion chamber and afterburner liners, as well as turbine blades.
The success of these applications depends on the ability to produce a
medium with controlled permeability in accordance with engineering requirements.
MKI Dynapore® has been successfully deployed in a variety of such
The Perfect Media for Transpiration
In severely heated components, transpiration cooling
allows a fluidic coolant that flows through the surface and exits the
component from the heated surface through small pores in the component.
Dynapore® is perfect for this application for many reasons:
- Excellent formability - new components fabricated with Dynapore®
can replace obsolete components.
- Porosity & permeabilty control - Dynapore® can be made to
allow a specific transpiring flow rate to control cooling characteristics
of the component.
- Mechanical strength & corrosion-resistance - all standard Dynapore®
parts are made with high-grade stainless steel, making the new components
very durable and be able to stand up against operating environments.
After passing through the Dynapore®, the coolant
will both remove heat from the surface and reduce the convective part
of any heating very efficiently. Some commerical turbine parts and rocket
engines presently use transpiration cooling. Consult
the factory today and find out how we can solve your cooling needs