Hi Rick-
Apologies, I may have made a mistake. Let me use the actual mass flow numbers
for my design and I'll try to illustrate:Total Ox Flow = 0.5709 kg/sec
Total Fuel Flow = 0.3172 kg/secTarget Mixture Ratio ~= 1.8:1 O/F
Now, what I was proposing is having an inner core of injection orifices where
the mixture ratio is slightly higher. This would be approximately 2.1:1
O/F.Inner Core Ox Flow = 70% of 0.5709 or 0.3996 kg/secInner Core Fuel Flow =
60% of 0.3172 or 0.1903 kg/secInner Core Mixture Ratio = 0.3996 / 0.1903 ~= 2.1
O/F
Then there would be an outer core closer to the chamber walls that is fuel rich
in order to reduce the adiabatic combustion gas temp near the wall as well as
gas side heat transfer. This would be approximately 1.35 O/FOuter Ox Flow = 30%
of 0.5709 or 0.1713 kg/secOuter Fuel Flow = 40% of 0.3172 kg/sec or 0.1269
kg/secOuter Mixture Ratio = 0.1713 / 0.1269 ~= 1.35 O/F
If I add up the Fuel and Oxidizer flows I *believe* the total O/F ratio is the
same but the lower mixture ratio toward the walls could (might) theoretically
help more with cooling without the subsequent reduction in performance caused
by more traditional film cooling.(Recalculated) Total Ox Flow = 0.3996 + 0.1713
= 0.5709 kg/sec(Recalculated) Total Fuel Flow = 0.19032 + 0.1269 = 0.3172
kg/sec(Recalculated) Mixture Ratio = 0.5709 / 0.3172 ~= 1.8:1 0/F
Kind Regards,Graham
On Saturday, November 26, 2016, 12:07:08 PM EST, Rick Dickinson
<rtd@xxxxxxxxxxxx> wrote:Graham,
Your numbers don't seem to add up to 100% for either the inner or outer
injectors, so I'm a little bit confused by what you're asking, and how you got
from those percentages to your mixture ratios. Can you clarify a bit, please?
Thanks,
Rick "confused" Dickinson
On November 26, 2016 8:47:00 AM PST, Graham Sortino
<dmarc-noreply@xxxxxxxxxxxxx> wrote:
Hi -
I was reading through the heat transfer / cooling sections in Huzel and
Huang and I wanted to ask two questions, which I’m struggling a bit
with:
In regards to #2, I’m working on a LOX/Kerosene 500 lbf engine running
at a 1.8:1 mixture ratio and I’m very tempted to try this but I wanted
to see if anyone has experience or advice with this? I'm not sure that
I recall anyone on Arocket who mentioned using this injector patter but
it seems like it could be quite beneficial. Essentially, what I was
thinking of doing is as follows:
Inner Injector Rings:
60% Kerosene Flow / 70% LOX = 2.1:1 mixture ratio
Either unlike triplet or like doublet configuration
Outer Injector Ring:
40% Kerosene Flow / 30% LOX = 1.35:1 mixture Ratio
Unlike doublet configuration
Kind Regards,Graham
