ram/scramjet engines principals

i do understand how the rocketengine works
It's all about that unbalanced force in one end of the combustion chamber that creates thrust.


The principal is the same in a jet engine....there is a point where the thrust is concentrated


but I can not understand how the ram/scramjet produses thrust . The fuel/air mixture just flies through
the whole engine which is just a complex tube.

I am not daubting it's capability to create thrust i just don't understand it

Well, it doesn't just fly through.

It does have a combustion chamber. And intense pressure is built up within that chamber during combustion. The geometry of the ram/scram, along with the combustion creates the same thrusting effect from the mass eflux as out of a normal jet.

it is that geometry that i am asking about aspacually that of a scramjet

Here is a real good basic link. And I will look for more complex for you, ok?

www.allstar.fiu.edu...

go almost to the bottom.

Have to agree with vorazechul here cause a jet engine seems a complex device yet it works on a simple principle.

I do know that the scram jet is an engine that requires much more air in order to function as it burns on a leaner principle. I think the real issue is getting up to the required velocity in order to take advantage of the design principle involved.

This seems the intermediate step on the road to very high technology, the marrying of myriad techs to produce a greater whole effect.

Well, a scramjet actually has to have an alternative powersource to get to its operating conditions (i.e. required speed).

Both the ram and scram have to have alternative power sources to get started.

Here's something with some a little more meat!

www.mie.utoronto.ca...

The only requirement for creating thrust is that the eflux from the engine has higher energy than the intake.

The ramjet creates this increased energy by first compressing the air at the conical intake, which creates fairly high temperatures. This hot compressed air then passes over the fuel injectors, combusts through the combustion chamber, and hits the exit nozzle - voila, increased eflux velocity! and thrust!

but i do need more detaild info on the construction to see how thrust is acheaved.
And the lack of info on that scramjet is disturbing ..not only is that a jet engine without a compressor and a turbine but it uses a much complexer way of transforming the combustion process in thrust with strange geometry of the whole engine
If you could find something to help me it will be great

Did you see my last post? I'm asking because I just am not sure if you missed it or not.

Let's step through it from the intake back:

The air comes in at the conical intake and is compressed as it goes over the "choke" point. This compressed air is VERY hot, so when it hits the fuel injectors, the fuel ignites. The combustion of the fuel accelerates the air (the enthalpy of the air is increased), it then hits a venturi tube, which accelerates it further.

A scramjet is a little different in that it injects and ignites the air at supersonic air speeds (the injection/combustion point is moved to just past the choke point in the conical intake). The nozzle in a scramjet is the expansion that occurs at the backside of the conical intake. Usually, the fuel in a scramjet will be hydrogen.

I will try to find some more links for you, but I hope this explanation helps. Basically, the minute you ignite the fuel you have increased the internal energy of your airflow, then you pass it through the correct geometry (venturi for subsonic, expansion for sonic) and it accelerates further. These two increases cause the thrust.

This is a very good one here, guys. It shows more detail in the combustion area and what is referred to as the "flame ring" that is the fuel injector. It requires very little energy at this flame ring for the combustion since the air is already highly compressed and at the elevated temperatures.

Also, it shows the venturi tube at the exit.

students.bath.ac.uk...

i just missed your post when i was sending
Your last one did make the thing clearer though

I have written a small page about Ramjets and Scramjets engines:

www.air-attack.com...

Also, you should realy check out the NASA "EngineSim" Java applet.
www.grc.nasa.gov...

Zion,

Very nice page!

it's as you have made your site for me a good one