The only exception would be if they are in a compound where the chemical
bonds contribute energy when broken during combustion.
This is the case with the compound under investigation.
Ken
On Tue, May 3, 2022 at 11:16 AM William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
Barry:
I’m not clear why alloying two metals would change their reactivity while
combusting: the programs—correctly, I think—simply treat the alloy as two
separate propellant ingredients.
Bill
On Tue, May 3, 2022 at 12:01 PM Barry Jolly <1bcjolly@xxxxxxxxxxxxx>
wrote:
I don’t know how to deal with your questions. Not enough education I
guess. My thinking is that the chemical equilibrium programs are based on
minimization of Gibbs free energy. How does one derive a heat of formation
value for an alloy of a small amount of lithium mixed with a large amount
of aluminum? Furthermore, how does one anticipate the mechanisms involved
in combustion of that alloy? I guess what I am trying to figure out is how
a program based on chemical oxidation/reduction reactions can predict a
performance increase caused by the method an intimate mixture of two metals
reacts. I read what I could find on the research of Alitec and they used a
chemical equilibrium program in their research. I find it amazing that a
program can predict a performance increase caused by different boiling
points of two metals. I am doing a poor job of communicating my thoughts
so will quit here. I need a face to face with a professor who can answer
my questions.
Sent from my iPhone
On May 3, 2022, at 13:11, Ben Brockert <wikkit@xxxxxxxxx> wrote:
Wouldn't that show up as variation of c* efficiency? The models assume
the chemicals are fully involved, if a significant amount of propellants
are going out the nozzle unreacted then there would be a performance
shortfall between the real motor and the model.
Does non-lithiated HTPB run at 85% c* typical?
Do lithiated rocket programs take into account that lithiated propulsion
engineers will be less worried about performance numbers?
On Tue, May 3, 2022 at 6:28 PM Barry Jolly <1bcjolly@xxxxxxxxxxxxx>
wrote:
Question: Do computer programs such as Micropep and NASA’s CET85 have
the ability to predict improvements in parameters, such as Isp, due to
changes in combustion phenomena? From my understanding of Alitec’s
explanation, their propellants increased performance is due to a difference
in boiling temperature of lithium as compared to aluminum in alloy form
causing an explosion of the alloy into nano-type particles which burn very
close to the surface of the propellant. Such explanation appears to me to
be based on burning characteristics of the propellant rather than
differences between enthalpies of propellant reactants and exhaust
products.
Sent from my iPhone
