[AR] Re: Nozzle shapes
- From: "contact@xxxxxxx" <contact@xxxxxxx>
- To: arocket@xxxxxxxxxxxxx, Ben Brockert <wikkit@xxxxxxxxx>
- Date: Wed, 13 Nov 2013 09:25:40 +0100 (CET)
I have seen this Q&A before, and was always wondering what exactly is meant by
"more conical Soviet nozzles" and "worse combustion efficiency in Soviet
chambers"?
Method to design optimal nozzle contour was developed in Soviet Union 1 or 2
years earlier than Rao developed similar method in USA. First engine with such
nozzle was RD-219 for R-16, developed in 1958-1961. Since then all Soviet
engines were developed with optimal nozzle contour, including of course all
staged-combustion engines.
The only engines with "conical" nozzles (actually - with "radius" nozzles) were
RD-107 and RD-210...214, developed in first half of 1950s.
Concerning combustion efficiency: "traditionally" almost all Soviet engines had
swirl injector elements (either single or two components) which provide better
atomization and mixing compared to jet injector elements "traditionally" used in
US engines. Since earlier 1960s, almost all engines developed in USSR were
staged-combustion engines, with swirl injectors for liquid component and jet
injectors for hot gaseous component. Such combination provides even better
atomization and mixing.
Best regards
Alexander Ponomarenko
http://www.propulsion-analysis.com
> Ben Brockert <wikkit@xxxxxxxxx> hat am 12. November 2013 um 20:35 geschrieben:
>
>
> Anyone have further info to back this up, or Russian nozzle design
> logic translated into English?
>
> From a powerpoint on nozzles by D. R. Kirk of FIT:
>
> Q: Why do U.S. nozzles look more like a polynomial contour and Soviet
> nozzles look more conical?
>
> A: (Jim Glass, Rocketdyne)
>
> Interestingly, Soviet nozzle designs have a 'different' look to them
> than typical US designs. US designs are ‘truncated Rao optimum’
> bells, usually designed by method-of-characteristics methods. Soviet
> nozzles, to US eyes, look more conical than ours. Ours have that nice
> ‘parabolic’ look to them - less conical. One would suppose the
> Russians are fully capable of running M-O-C and CFD codes and thus
> their nozzles, if optimum, should look ‘just like’ ours. Since they
> don't, I've always wondered if they know something we do not. In my
> experience, the US is better at combustion engineering (minimal C-star
> losses) but has fairly substantial losses in the nozzle (aerodynamic
> losses). The Russians tend to reverse this, throwing away huge gobs
> of energy due to incomplete combustion and then using a very efficient
> expansion process to get some of it back. The bottom line is both
> design approaches appear to yield roughly the same Isp efficiency...
> One wonders what would happen if one were to mate a US combustor to a
> Russian nozzle…
>
Other related posts:
