It's probably also worth adding that with a typical blowdown hybrid system
(assuming it's an unregulated blowdown), you have a regressive oxidizer
injection coupled with a varying port geometry to substantially further
complicate an already very complicated set of conditions for theoretical
modelling of a post combustion chamber.
Troy
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of Troy Prideaux
Sent: Tuesday, 16 November 2021 9:13 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Dimensioning of post combustion chamber PCC of hybrids
I'm guessing PCC is post combustion chamber? Not pre combustion chamber. Not
that it matters, because it's sized by experimental measurement. Too many
variables with injection, mixing, chemistry, geometry, local turbulence,
fuel regression, temperatures etc etc etc.
There is a tiny section in Kuo & Chiaverini's Fundamentals of Hybrid
Combustion and Propulsion with a couple of equations, but I don't think
they'll be helpful.
Troy
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx] On Behalf Of Bruno Berger
("bruno.berger")
Sent: Monday, 15 November 2021 6:06 PM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Dimensioning of post combustion chamber PCC of hybrids
I am currently supporting a student project building a hybrid engine. I am
more the liquid guy and the question came up several times about the design
criteria's of the size of the PCC of a hybrid. I know you size it normally
in the range of 0.5-1.0 of diameter of the grain. But to me it's clear that
it depends on several factors (A grain with a big central port needs IMHO
more PCC than a multiport grain). I haven't found any useful info's yet :-(
Any suggestions (maybe a link to a scientific/engineering report?)
Thanks a lot!
Bruno
"At that time [1909] the chief engineer was almost always the chief test
pilot as well. That had the fortunate result of eliminating poor engineering
early in aviation" (Igor Sikorsky)
--
Bruno Berger
IBB.ch engineering GmbH (LLC)
E-Mail: bruno.berger@xxxxxx <mailto:bruno.berger@xxxxxx>
PGP: https://www.ibb.ch/various/Bruno.Berger.asc
S/MIME: https://www.ibb.ch/various/Bruno.Berger.crt
WWW: https://www.ibb.ch