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