Damn it, knew I missed some important ones and Norman’s post just reminded me:
Hydrogen has a lesser requirement to burn completely given its MW: regarding
performance.
Troy
From: Troy Prideaux [mailto:troy@xxxxxxxxxxxxxxxxxxxxx] ;
Sent: Friday, 14 August 2020 10:33 AM
To: 'arocket@xxxxxxxxxxxxx' <arocket@xxxxxxxxxxxxx>
Subject: RE: [AR] Re: Thrust Chamber Manufacture
You can push more through a smaller office with a lower pressure drop
The issue of coking or clogging of fine orifices is theoretically eliminated.
As you said, the coolant qualities
The 1st point provides more potential for the utilisation of “naturally” porous
matrix from additive processes or even sintering processes.
Troy
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx] On Behalf Of roxanna Mason
Sent: Friday, 14 August 2020 10:19 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Thrust Chamber Manufacture
Why only hydrogen, coolant qualities, beside the obvious c* advantage?
K
On Thu, Aug 13, 2020 at 4:31 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx
<mailto:troy@xxxxxxxxxxxxxxxxxxxxx> > wrote:
I've (for a while now) thought that if you can additive manufacture your
chamber and are particularly constrained to using hydrogen (for one reason
or another) , then this option is quite worthy of some exploration.
Troy
Behalf Of Henry Spencerin
Sent: Friday, 14 August 2020 9:05 AM
On Thu, 13 Aug 2020, Doug Jones wrote:
Transpiration cooling makes for thick, heavy walls, low Isp, and
complicated machining. Why bother?
Depends on what you are trying to do, in the way of performance and other
constraints. Right now, it makes sense only for extreme requirements.
P&W used it extensively in their 60s/70s high-pressure work (culminating
their SSME proposal), having concluded that it was the only way to makethings to
lightweight high-pressure engines with unlimited working life. It was not
because they weren't familiar with regen... :-)
Thick, heavy walls and low Isp are not inherent in the concept. They are
consequences of trying to do it with today's materials, which either don't
provide precise control of coolant flow (and hence require overdoing
guarantee adequate cooling coverage everywhere) or incur a lot of massmodern
overhead for even semi-precise flow control.
Transpiration is used very successfully in several other areas, e.g. all
gas-turbine blades are transpiration cooled. Keeping the heat out of themetal
is inherently better than trying to pull it back out once it's in... ifthe details can
be made to work adequately. Right now it's hard to do for rockets.Hi-res 3D
printing (better than today's), for precise design of wall microstructure,could
change that.
Henry
