kathy thornton continues to ignite fuels
that are
have been deployed onto a thin fiber
got the latch to rope shape
that's affirmative valve this is a real
nice drop and we'd like to continue on
at step
delta decimal five
copy that
once again we are able to see
experiment video from three of the
experiments that are being processed
onboard space lab
stand by rommel and kathy can you
confirm it's still burning
it just extinguished and there's a
little bit of clouding in the chamber
this time that was really strange
looking
in space lab huntsville for kathy we are
going to run with the fsdc fan on for
this next three millimeter run and when
you're ready to copy the setting i've
got that for you
kathy thornton has just released another
drop of fuel onto the fiber
the fuel has just been ignited
you can see the combustion products or
soot that are being released by the
burning fuel
hello worcester mass
my name is al sacco and i'm from
worcester mass i'm a ps on this flight
united states microgravity lab number
two we're doing a lot of science
experiments on a whole variety of
different fields biotechnology material
science crystal growth fluid dynamics
fluid physics and combustion
and we're going to talk a little bit
about all of these things with you guys
today before we do
let me introduce or let them introduce
themselves the redshift first we'll go
to our commander the boss
hi i'm ken bowersox i'm from bedford
indiana and i'm the mission commander on
fps 73.
i'm kathy thornton and i'm the payload
commander on this flight
and i'm kent romer you're from delaware
colorado and i'm the pilot on this
flight
and that's the redshift
can we have the first question please
okay for questions regarding fluid
experiments worcester south high please
go ahead
this is hosanna
my question is what is the purpose of
the contact angle experiment
well in order to understand the purpose
of the contact angle experiment you
first have to understand two variables
that are involved with it one is called
surface tension
and the other is contact angle and
they're related
surface tension really can be simply
thought of as how molecules like each
other that they like each other a lot
they have a very high surface tension on
the other hand what you also have to
balance is how they like the materials
they contact
and those are called adhesive forces
adhesive forces how the liquids
like the solid so what you have when the
contact angle experiment is a balance
between what they call cohesive forces
or surface tension
and adhesive forces so how it likes the
wall and when those two balance
and they're balanced by gravity that's
really how far up the liquid goes
now in in space the reason we come to
space to study surface tension is
primarily because it dominates and let
me give you an example of that
you see in space the orange juice the
molecules like each other and they form
a sphere if you were to do that on the
ground of course it would cling to the
sides of the vessel and these are called
again surface tension is something
called a cohesive force
steven bellick from the accelerated
learning laboratory
hi i'm nick piquette from north high
school
hi i'm beth quinadamo from north high
school
hi i'm reggie hill from north high
school
hi i'm josh robert from dardy high
school
hi i'm tanisha westa from north high
school and our question is
how does the surface tension and contact
angle react in space when soap is added
and why
soap is a what we call a surfactant and
what that does is reduce the surface
tension
and in space it reduces the surface
tension by the same amount it doesn't
change at all in space but again what
you can see is you can see the effect of
that so factor a lot more in space
because you have a one-sixth gravity
component and therefore surface tension
dominates over gravity and we can
explore that but it really doesn't
change
anything more than it does on the ground
the ground and space are very similar
when you add soap as a surfactant
i'm katie already from doing another
question please
i am igor vishwandority high school
and i'm tom davao from doherty high and
our question is in the contact angle
experiment what would happen if the
slides were of different materials and
sizes and would other liquids change the
result
well i hope uh with what i've explained
to you so far that surface tension and
contact angle are basic properties of a
liquid and its interaction with the
solid
so those aren't affected by space
however every time you change the liquid
or you change the solid that it's in
contact with that is the material then
you in fact will affect the contact
angle experiment how high it rises but
the size that is the size of the
materials or even the amount of liquid
that you put in really doesn't have a
major effect on that either in space or
on the ground
next question please we have five
minutes remaining in worcester please go
ahead with the next question
hi my name is hong tran from north high
and i was wondering if the mass of an
object can break its service tension
you know that's that's another very
interesting question and you got to
think about it a little bit surface
tension again is a basic property of a
fluid
and it really doesn't
change whether we have whether we have a
large mass on it or a small mass on it
the surface tension is the same however
what you see
is if i look at an eye dropper and i
squeeze out a little bit of liquid on
the ground as that liquid grows it gets
very heavy and as it gets heavy it
elongates the drop and eventually it
falls off now the surface engine
surface tension of that material didn't
change it just became so heavy
that the adhesive forces were overcome
by the cohesive forces excuse me the
cohesive forces were overcome hello the
cohesive and adhesive forces were
overcome by gravity is what i'm trying
to say hope here up here that wouldn't
happen of course and you saw that with
the straw when i squeezed out the orange
juice it just sort of hung there as a
sphere
so surface tension really doesn't change
it's not broken by mass
but you see it looks that way and it
seems that way uh because of your
observation in the one gravity
environment
please
hi my name is joella tafani from south
high my question is is there a
difference in velocity of the spreading
pepper in space
well to be honest with you we didn't
spread any pepper in space on this
flight at least we haven't yet
but
i would expect that there may be a
difference in in velocity and the
difference in velocity wouldn't be
because of the surface tension effect
but
because of convective effects
temperature differences and that's
additive so you'd get not only the
surface tension effect but in addition
to that you may get some convective
effect so you probably see a difference
in the velocity of the pepper itself
moving across the surface
can i have another question please we
have one minute left in worcester time
for one last question my reaction
there's a reaction would a ball of water
disperse if you put pepper into it
well we haven't run that experiment
either but i can tell you the answer to
that
just like sprinkling
pepper on a liquid surface what you'd
see up here is you'd see the pepper just
form around the outside of the sphere of
liquid
and for every action there is a reaction
as the pepper touch the surface of the
liquid the liquid would touch back with
exactly the same force but what you'd
see is because of surface tension that
pepper would just adhere to the outside
of the drop
and it would form all the way around the
drop you'd see a uniform distribution of
pepper all the way around the drop
hi my name is prubali chakraborty and
can fiber supported drop combustion be
used in the shuttle's engines to make
maneuvering simpler and are there any
real-life applications
yeah that's a good question too and i
have a navy aviator here and a fighter
pilot that's going to answer that for us
and also the pilot of the shuttle so
this is kent
thanks sally that's a great question and
the answer is maybe that can help us
maneuver the shuttle
the uh and also in real line
applications there are many i'll start
out by saying as well as the shuttle
from having better combustion and the
f-14 i used to fly as well as the car
that people drive even the heater and
water heater in your home it can help
them be much more efficient and the
reason we study that up here in
microgravity is without the influence of
gravity and without convection
the burning is much more even in a
sphere and it burns more slowly so we
can control it and much better analyze
it and hopefully come up with more
efficient combustion processes and fuels
and additionally that would also result
in less pollutants so it would help the
environment also
next question
hello my name is jill feckler
do different flammable liquids form
different shapes when they burn and are
the materials you're using different
from ours
that's a good question as i understand
the materials that you are using are
petroleum distillate which is a mixture
of all different kinds of petroleum
products we're trying some pure
fuels up here or very simple mixtures
we're using some methanol and water and
a few other mixtures and
because they are liquids they form a
sphere
here in space
just like the orange juice you saw
floating around but we don't want these
burning droplets floating around the
space lab so we can find them by putting
them on a fiber
so there are spherical drops on a fiber
the different materials often the same
shape however the the combustion of the
different materials is significantly
different the methanol was burning with
a very very faint blue shell of flame
and some of the other products were
burning with yellow or several or blue
and yellow alternating kind of
flames you have another question
yes my name is jessica huddy
did your flames move around or vary in
size and shape due to air currents and
do the flames produce any visible
products such as smoke
that's a very good question that some of
the things that we're trying to explore
up here we have done some of the burns
without air currents and we get a
completely spherical shell of flame
and others we have done with air
currents and we get a teardrop shape
where the the combustion products and
the vapors that are burning are moving
along with the air currents it also
changes the color of the flame because
with air currents we're feeding more
oxygen
to the
ball of fire
and uh other when we're not having air
flow it's uh the oxygen has to diffuse
into the combustion zone so it's a
little bit slower burning process
also burns bluer whereas we have airflow
we have a little bit of a yellow color
my name is ray marquette
what percentage of times did you get a
good flame and how long on average did
your flames last
we've had a little bit of trouble
getting the droplets deployed on the
fiber but once we get them on the fiber
we get ignition every time
and uh we it burns from uh on the
average of five or six seconds for a
small drop to a five millimeter drop was
going as long as 25 or 30 seconds which
is a lot longer burn time than you're
getting on the ground with your
experiment
hi my name is geralyn waters
and my question is do you think anything
besides the difference in graphic
gravity could cause the flames to differ
gravity has a lot of effects on the
on this experiment and yours
in your experiment you're burning a tear
drape teardrop shaped
fuel because gravity is pulling it down
here we start out with a spherical drop
of fuel and also because of convection
which is another effect of gravity the
combustion products and actually the
vapors that are burning are rising in
your experiment and oxygen continues to
be supplied from the bottom here we
don't have that so we're looking at
diffusion of oxygen into the flame front
to continue to feed it which is a little
bit different than what you're doing so
gravity is certainly the major effect up
here the lack of gravity is the
difference in what we're doing and what
you're doing down there
my name is jared shooter
do you have to replace the filament
after each time that you burn the fluid
you know another good question that's uh
we didn't replace the filament every
time but we do replace it periodically
and one of the reasons for that is we
get foot deposits we had carbon deposits
high molecular weight carbon materials
and what do they do they change the
surface tension of the liquid and how it
interacts with the solid itself that can
result in a variety of different things
not the least of which is the drop
moving along the filament itself in
addition to that it can change the heat
transfer rate how heat is leaving the
filament which affects the studies that
we're looking at
so we don't replace it all the time but
if it looks like it's getting a little
then we do in fact replace it
my name is kate gehart does the type of
filament have an effect on the result of
the experiment
yeah very much and that's another
very interesting question because one of
the things that we're looking at is is
all the different heat transfer and mass
transfer effects how oxygen comes into
the flame and that light blue flame that
we see as a result of what we call a
diffusive flame oxygen is not convecting
ends not being brought in by other
molecules as a group but coming in
individually it's a diffusive flame
how the heat is taken out of the
filament is very important because some
of the heat is being conducted down the
filament so if we change that material
we can change it from a metal which is
very conductive
to a ceramic which we're using up here
which is a little bit less conductive
and that changes the entire burning rate
of the film
of the flame excuse me
and changes what we see in the dynamics
of the flame itself so the material the
thickness of that material are very very
important it's also important in
microgravity to make sure again the
liquid and the solid are compatible in
the sense that the liquid to a certain
extent but not too much what's the solid
in other words we don't want it to like
to solid too much so it won't maintain
its sphericity but we'll spread along
the filament but we do want it to
maintain its contact with the filament
we need to light the filament a little
bit
hello my name is ann johnsy my question
is is the flame isolated to the coil of
the filament or does it move away from
the filament so just the fluid is
burning
well first again we're not using a coil
up here we're using a uh filament just a
straight line
material straight string
but
you should
you probably remember from studying this
that in fact the liquid is not burning
but the vapors from the liquid are
burning and that's what we see as well
we see a shallow or a halo of burning
material that's displaced slightly from
the liquid of the fuel
and that's what burns the vapor
next question please
and this is the last question from
louisville science center please go
ahead
my name is tom fulda
and i was wondering would the amount of
electricity used in the experiment
change the rate of combustion and would
microgravity have any effect on this
that's another uh interesting question
we have to think on that a little bit
but
certainly when you put in more
electricity into your filaments now
we're not doing it exactly that way
we're igniting it from an external
source we're not putting electricity
through it
i wouldn't expect the electricity to be
affected by the microgravity at all
but by increasing the electricity in the
filament if we were doing it that way
like you're doing it on the ground
increases the rate at which the filament
heats and therefore
impacts the rate at which the vapor is
combust so in fact as you change the
electricity you may see an effect but
that would be again a function of the
material that you make your your coil
out of and the rate at which you put
electricity in it would be a very subtle
and difficult thing to measure for you
but it is measurable on the ground in
microgravity that wouldn't affect us
very much first of all but because of
the way we're doing the experiment but
in addition to that even if we were
using electrical way to heat the
filament i wouldn't expect uh
microgravity to affect
electricity very much up here so that in
and of itself would not be affected by
microgravity the same thing that was
affected on the ground though would be
affected up here in the sense that the
rate at which you put the electricity in
how much the thickness of the material
and what that material it is how much of
a conductor it is will in fact affect
that burning rate
you