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
