Rushd:
I’m thinking your experience doing propulsion at Virgin Galactic has left
you with far more knowledge on these matters that is common among amateur
rocket builders.
Perhaps a graduate program of study under someone who knows this area well
might be the right approach?
Bill
On Mon, Feb 20, 2023 at 1:34 PM Khaled Julfiker, Rushd <rushd@xxxxxxxxxxx>
wrote:
Hello All,
I am passionate about Liquid Rocket Engines, especially injector
hydraulics and combustion. I am trying to model LRE combustion.
I know about L* and how to size a combustor based on L*. But now I am
trying to understand how to size a combustor based on injector pattern,
jet/fan/sheet breakup length, and droplet evaporation/burning time. I know
some linear stability analyses (Kelvin-Helmholtz, TAB models, etc.) and
empirical relations for jet, fan, and sheet breakup lengths. I have also
modeled single droplet burning (based on the Spalding model), which can
tell me how far it travels before it is consumed. The injectors I am
considering are pintle (LOX-RP1 and NTO-MMH), co-axial swirls
(LOX-Methane), and like-doublets (LOX-RP1).
Now I am trying to model spray patterns, droplet size distributions at
different spray locations, droplet interactions, and how they influence the
burning and evaporation rates. Here I get a little fuzzy. Is Rosin-Ramler
distribution one way of describing SMD of droplets? Is this the right way
to go? What other things should I consider for this model? What would be
some good references for analytical models and CFD?
Later I will also try to simulate combustion in supercritical conditions.
My understanding is, in Subcritical conditions, evaporation time is the
rate-controlling process, whereas, for Supercritical conditions
(high-pressure rocket engines), surface tension becomes negligible. Hence
propellants cannot form droplets, and diffusion mixing becomes the
rate-limiting process. Any reference I can use to simulate this would be
helpful to me.
Finally, how can I distribute the injector elements for efficient overall
mixing? Is it based on the Rupe number? Any reference would be appreciated.
And if my understanding is correct, I must keep the maximum heat release
regions away from pressure anti-nodes to avoid instabilities?
I know these are a lot of questions. But this forum has expertise in this
field, and I would appreciate your direction.
Thanks.
Russ