In my engine with a LOX/kerosene mixture ratio of 1.8, it was pretty goopy
after a run. I didn't measure it though. There was a gooey later followed by a
more durable layer that took a scotchbrite pad to remove. There were however
several places on the chamber wall where bare metal was visible. The orifices
were aligned well but the LOX orifices were pointed toward the chamber wall due
to space and design constraints.
-Bob
On Nov 29, 2016, at 14:24, Doug Jones <djones@xxxxxxxx> wrote:
The LOX-cooled chamber we tested at Rotary Rocket (Pc>100bar, thrust ~10 kN)
produced phenomenal soot layers, up to 4 mm thick in the chamber after runs
of only a few seconds duration. These were a pain in the neck during engine
teardown and inspection, I was as grubby as a chimney sweep. The LOX
_seriously_ over cooled the chamber, and the soot layer only made that more
so.
It had a transpiration cooled throat using water (predicted heat flux 130
MW/m2) so I don't know what the soot thickness through the throat and nozzle
would have been for a fully regen engine. The injector had no mixture ratio
biasing and no film cooling.
Doug Jones, Chief Test Engineer
XCOR Aerospace
1325 Sabovich
Mojave CA 93501
(661) 824-4714 x117
cell 661 313-0584
On 11/29/2016 12:06 PM, Henry Spencer wrote:
On Tue, 29 Nov 2016, Graham Sortino wrote:
...does anyone have a reference to a paper discussing thermal deposits on
Rocket Engine chambers? ...it warrants me understanding it better before I
even consider including its effect in thermal calculations.
Schoenman, "LOX/Propane and LOX/Ethanol Combustion Chamber Heat Transfer",
JP&P 7.4 (July-Aug 1991) has some discussion of it.
The bad news is that it's almost impossible to calculate how much it will
help, or not, because sooting is poorly understood and nobody's got a good
handle on predicting it.
Henry
