In
hypersonic vehicles, regenerative cooling is used to handle
the thermal load encountered in the combustion chamber. In this method,
the fuel itself flows through a cooling channel and is circulated
around the combustion chamber. The channel is made of porous material
that enables fuel to also partially flow directly from the channel
to the chamber by transpiration, which cools the wall by internal
convection. The exposure of the fuel to high temperatures results
in fuel pyrolysis producing carbon particles (coke). These particles
are transported by the fuel and deposit inside the pores of the material
resulting in a decrease of permeability of the medium. This process
is very complex since it affects the heat transfers which generate
the fuel pyrolysis and the formation of the particles. A test bench
is developed in the current work to study the transient effect of
the key parameters (i.e., filtrating mass flow rate, a load of particles
in the flow) on the particles’ transport and on their spatial
distribution inside the material. In the first part of the study,
a porous medium with 3 mm thickness is used. It is found that with
an increase in operational time, the powder mass accumulated inside
the porous medium increases. In the second part of the study, different
thicknesses (6, 9, and 12 mm) of porous medium are tried, to study
its effect on particle transport. Particle transport is a function
of pressure drop; therefore, the thickness of the porous medium is
progressively increased at the same inlet mass flow rate which in
turn modifies the pressure drop across the porous medium. More interestingly,
the particles accumulate in the first 3 mm thickness of the upstream,
while in the downstream on the opposite side of the porous material,
almost no powder is found. Additionally, the pore Reynold’s
number inside the porous media and the Reynold’s number of
the fluid inside the permeation cell are determined to explain the
transient and spatial evolution of clogging inside the porous media.
In all the studied cases, the amount of powder transported through
the porous media or collected downstream remains absent.