[sugpro] Re: End Burner
- From: "Steve Peterson" <dmarc-noreply@xxxxxxxxxxxxx> (Redacted sender "steve_peterson" for DMARC)
- To: sugpro@xxxxxxxxxxxxx
- Date: Sun, 10 Sep 2017 15:19:05 -0700
On 09/10/2017 10:18 AM, Mike Smith wrote:
I was hoping that by switching nozzles to Durham's putty that erosion
will prevent a clogged throat. No convergent section will create a
"shelf" behind my steel disk to collect slag. The addition of silicone
oil was to minimize slag formation. About the only place this motor
could clog would be the hole I drilled in the steel disk. Suggestions
on how to keep that hole clear of slag? What about higher chamber
pressure? I was shooting for 300 to 350 psi.
I have never fired a nozzle with Durham's (or anything else like that)
so I can't speak to erosion.
I honestly didn't ever get to the point where I felt like I fully
understood what was going on with the clogged nozzles (they were all
graphite since they were super easy to turn). The motor would cato and
I'd find bits of the nozzle, but not enough to reassemble a complete
one, so all I could do was note the large amount of slag and assume that
was the problem. The best indicators were nozzles that *almost*
catoed--during post-firing disassembly/inspection I'd see globs of the
stuff stuck somewhat randomly around the convergent section, in some
cases *almost* clogging the nozzle. As I recall, the divergent section
and the very narrowest part of the throat were almost clear of the
stuff, suggesting that somehow it was "oozing" or "dribbling" in sizable
globs which gradually coalesced to the point where the nozzle finally
clogged. That's pretty much pure speculation on my part since I had no
way to really observe what was going on.
I believe, but can't say definitively that higher pressure will help-as
I mentioned elsewhere, my low--pressure regime was down around 200 psi,
as I recall.
Burn time will also be a factor--if you're only going to burn for a few
seconds, say less than 10, it may be that the slag produced wouldn't be
sufficient to work its way to the throat and clog it.
I had noticed some small amounts of slag in bates grain motors that had
large throats and ran at much higher pressure, but never gave it any
thought until I started working with small throats and lower pressures,
and using "nozzle down" instead of "nozzle up" arrangements for static
tests.
--Steve
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