On Mon, 2002-09-09 at 00:41, John Carmack wrote: > > > > >This is a very incomplete drawing, and it is a cross sectional. My next > >step is to find a mesh generator package and start finding the problems > >with combustion and exhaust flows in the geometry, modify the curves > >accordingly, then start thinking about how to actually build it and hold > >the plug in place. > > > >Dave > > IMHO, doing CFD is going to be a complete waste of time. >
Depends on what exactly you are looking for. What is the expansion ratio at the end of the spike in my drawing? > For instance, what is the difference between a 15 degree cone and a > perfectly calculated bell nozzle? 2%? That is a difference that will be > swamped by catalyst pack issues and experimental error. Maybe. But there are other issues in the flow field that I want to get a better idea of. Aerospikes just don't seem to be as simple as bell nozzles - at least for me - and I want to better understand them. > > You mention combustion, but we are still talking monoprop here, > correct? Yes, decomposition I should say. AllSPD is designed for "combustion" analysis. From droplets coming into the chamber through actual combustion and exhaust out the nozzle. Unfortunately, catalyzing peroxide won't work in the program, so I'll just have to specify a turbulent flow at the cat pack exit plane. Not perfect, but should give me a clue as to how it will work in reality. > Regarding performance, I would be very interested in seeing some > simulations of expected performance for a low chamber pressure + altitude > compensating nozzle versus a high chamber pressure fixed nozzle. I may run > some of these myself if nobody beats me to it. > http://flab.eng.isas.ac.jp/member/ito/web/research/introduction.htm Aerospikes have another advantage in size and mass over a bell nozzle. Of course, I just don't see it at our scale. Dave _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
