Hi. I'm Sally Bane, an associate professor
in the School of Aeronautics and Astronautics, and I also have a courtesy
appointment in the School of Mechanical Engineering.
We are here in one of my laboratories. I call this laboratory the
Plasma Aerodynamics
and Combustion Science Lab, CAPS for short.
This lab
is located at Purdue's Aerospace Sciences Laboratory, which
is located near the Purdue airport
and our aviation technology school. So my research
area, I have
pretty broad research interests, but they
really are focused in three major areas. The first is experimental
combustion dynamics where we look at
fundamentals of how fuels burn
of flame propagation and transition to detonation.
The second area is plasmas for aerospace
applications. I focus on what
we call ultra-short pulsed
plasmas or non-equilibrium plasmas. And the
applications I'm particularly interested in is using them
for combustion control and for aerodynamic flow control.
The third area is general plasma
and flow diagnostics looking at
new and state-of-the-art ways to
measure the characteristics of plasmas as well as
fluid flows and combustion flows.
So this is one of the smaller scale
combustion experiments that we have in this lab. You'll
see behind it on the wall a couple pictures
of very large explosions. So at Zucrow Labs
I have a 20-foot combustion tube that's about
a foot in diameter
So that's a very nice impressive experiment
but if we want to understand what's going on inside of the tube
like how, when we ignite the fuel mixture
how the flame accelerates
and transitions into a detonation, we need to have
a smaller scale more fundamental experiment.
So this is one of those experiments.
This is a detonation tube
a flame acceleration and detonation tube.
You'll see that it's
like a small version of our 20-foot tube but
in this case we have windows all along both sides.
So we're able to actually watch the combustion wave
as it propagates down the tube
and analyze what is causing it to accelerate
and in some cases transition to a supersonic detonation wave.
So my second area of research is
on using plasmas for aerospace application.
As I mentioned, I'm particularly interested in two applications.
One being control of combustion
and the second being aerodynamic flow control.
So I'll show you a couple experiments we have here
that are looking at those two applications.
So the first experiment here
is looking at plasma control of combustion.
So this is a burner.
and we have
a mixture of fuel and air that comes in
and up through the burner tube.
Inside of the burner we have a swirler
which generates rotation in the flow
and we then can
put a match or a spark in there and
light up a flame.
Is flame is what we call
a swirl-stabilized flame and it's a
small-scale version of the kind of combustion that you
would see in a typical gas turbine engine on an aircraft.
So once we have the flame established here
we can first study things about the flame itself
such as the stability of the flame
using pressure signals
so we actually have a couple microphones
for detecting
pressure fluctuations due to the combustion.
We also have it confined inside a glass
chamber so that we have optical access to
visualize the flame and to do other measurements such
as particle image velocimetry,
which we actually have set up right now and
I'll talk about in a moment or
other laser-based spectroscopic diagnostics.
 
In addition to studying just the dynamics
of such a flame
As I said we're interested in affecting those dynamics
using plasmas.
So it's a little hard to see but you can see
that there's metal rod sticking out here and
there's another one on the other side. These are electrodes.
And they
extend inwards and have two sharpened tips
at the exist of the burner tube.
What we do is we connect these electrodes
to a high-voltage pulse generator
and
we can then generate plasma in
the gap between the two electrodes. We then using
the diagnostics we talked about we can look at how
generating these plasmas
can force the flow and affect the
chemical reactions in the combustion.
So the second application I mentioned
in addition to what we call plasma-assisted combustion
is aerodynamic flow control using plasmas.
This is an area that's been around for about 20 years now.
Where people have been looking into
generating plasmas on the surfaces of
aerodynamic bodies. For example, on
the surface of a wing
and using the affects of the plasma on the flow
to improve performance of the wing, such as reducing the drag.
I also work in this area.
I am more interested in using plasmas to control
high-speed flows, specifically supersonic and hypersonic
flows.
Here on the table we have a couple examples of some
plasma actuators that we're developing. If
we're interested in aerodynamic flow control, we want to be able to generate
the plasma on the surface of an aerodynamic body.
So we
build actuators that look kind of like this.
where we have electrodes actually
glued or attached onto the surface. So this
is a desktop model where we again apply
the high voltage, and we generate plasma filaments
between these saw teeth.
This is the supersonic wind tunnel here
at the Aerospace Sciences Laboratory and this is the wind tunnel
I use to test my
plasma actuators. So I showed this before
this is a surface actuator which generates
plasma filaments.
What we do is we attach this
to a fixture
which slides into the tunnel and sits
flush with the surface
And we run the flow anywhere
from Mach .6 up to
Mach 3.5 depending on what nozzle we have installed.
And we can operate the actuator
and use visualization and
the existing Schlieren visualization
to study the effect of the plasma
on the supersonic flow field.
So I mentioned with all these experiments
the various flow diagnostics we do and that's really
my third area of focus is improving
the accuracy and utility of
high-speed flow diagnostics.
So in this lab we can do three different
flow measurements simultaneously.
The first is
basic Schlieren visualization
which is this light source in these
optics here. The second measurement
that we can do is measuring the flow velocity.
We do that using particle image velocimetry
or PIV.
Here we have a 10 kilahertz
PIV laser with the associated optics.
and it allows us to record velocity vectors at a rate of
up to 20 kilahertz. Right now you can see the PIV system
is set up for recording particle image
velocimetry of the swirled flow
out of the burner. But we also use this to measure
the flow in various combustion experiments
as well as the flow induced in our plasma discharges.
The third diagnostic allows us to measure the flow
density, and that measurement technique is called
background oriented Schlieren. And
it's a very simple measurement technique where here we
a dot pattern
which we place behind our
field of view of interest
and by looking at the apparent distortion
of the dots when you visualize them
through the density gradient field we can actually extract
the density of the flow. So the result is
for a given experiment
we can simultaneously see the flow using the
Schlieren visualization and measure
the velocity and density
using the PIV and background oriented Schlieren.
