Current theorys in fluid dynamics for jet propulsion

[hell18]

anyone know any theories being used for fluid dynamics? any formulas? I aint no physicist, I am just curious. Are there any developments today involving jet propulsion by going faster with only half the fuel? if that sounds right.

any help would be appreciated

 

[russ_watters]

Pretty broad question. And there are lots of formulas. Do a google search for "gas dynamics." And the first equation to know is the various forms of Bernouli's.

As far as efficiency, its really not that hard - you just have to make tradeoffs. An SR-71 for example has engines (turbo-ramjet hybrid) so efficient that its speed is limited only by the temperature at which the plane will melt. The efficiency increases as the speed increases. But as a result the engines are very INefficient at low speed so it takes miles of runway to take off.

By contrast, a turbofan is highly efficient at low speed, but less efficient at high speed.

 

[drag]

Originally posted by hell18
Are there any developments today involving jet propulsion by going faster with only half the fuel? if that sounds right.

There are attempts to build Scramjet engines which are
designed for hypersonic travel (Mach 5+). These are tubes
that do not even slow the air that goes through but
just add a bit of hydrogen and thus ignite the flow
through interaction with atmospheric oxygen. Unfortunetly,
these engines, for now, have huge problems to overcome.
They overheat in a matter of a few minutes and even seconds and
the egnition of the hydrogen in the thruster in such a powerfull
and quick airstream is extremely difficult to achieve. There are
also other ideas using other types of fuel with the general concept
being an air-breathing rocket where the oxygen comes from
the atmosphere as the air flows through the open thruster.

Live long and prosper.