supersonic valveless pulsejet

[ganuganu]

iam asking these questions because,from now on iam planning for my final year project..so even for my final year iam going to make on pulsejets..i want to do some analysis on pulsejets as well as ramjets and also i want to check the advantages of pulsejets/ramjet combination instead of turbojet/ramjet combination....

[Jutte]

Are you talking about the exhaust speed - or once you get to that speed as a whole?
Here is my 2cents worth about the topic in general once you get to that speed overall.
The main problem is not going to be your exit exhaust flow.
Variable nozzle systems,after burning units etc have overcome those problems.
The main problem is the supersonic or near sonic flow entering your intakes.
All Jet Turbines tend to rapidly suffer problems with turbines stalling, flameouts
and other nasty stuff under these conditions.Pulse jets will suffer intake and combustion consequences
Divergent intake ducting to reduce supersonic intake engine airspeed is one way of doing it.
Do research on the Concord engine systems or the variable spike on the Blackbird.
Next problems will be control surface reversal, Centre of pressure moving( that'll wreck your day big time), Supersonic
waves over structures etc causing destruction.(Take a long look at the F15, F18 airframes - then look
carefully at the engine intakes. There is a whole lot of engineering not very obvious there )
When you go supersonic you open a bad ass can of nasty whoopass worms.
Sure I reckon you can get a pulse to go supersonic - but it isn't going
to be your average engine and you better be prepared
to throw a lot of time and money at it.
Sure a ram jet after a pulse jet could possiblily get you there - but then you're back at the whole
intake problem again...

[ganuganu]

iam not going to make the whole thing in practical,i ll just create the design with proper dimensions for both ramjet as well as pulsejet..then i will simulate these things in a software to show it..i think making this in practical requires more practical as well as technical knowledge sir..so simply i will analyse the replace of turbojet/ramjet combination to pulsejet/ramjet....

[sadmemories20]

I think even in normal turbojet engine its nearly impossible to achieve mach 1 without making any special arrangement in the exit of the turbojet engines....

[nitro]

Personaly I think Valveless or Valved Pulsejets could if designed right could crack the speed of sound.Not much point though is there.

[Jutte]

Hi Sadmemories20,
Aerodynamics is the most important factor.
Airframe, materials,design -everything must work.
A huge engine will get you there.
"...without making any special arrangement in the exit of the turbojet engines"
Variable nozzles, reheat/afterburner etc - that will just get you there quicker.
Modern passenger jets have the potential to do it ( eg:727 - well not that modern - see TWA 841. DC-8-42 on August 21, 1961 .A China Air 747 also did it over the Pacific).
However it's not feasble due to fuel consumption,economics,airframe problems,people
complaining about sonic booms, and the ever present....
"When you go supersonic you open a bad ass can of nasty whoopass worms."

[luc]

A properly build ramjet would be capable of reaching maybe mach 2.5

Just a pointer ... But I do remember the SR-71 flying mach 4 (Or Very close) ... And correct me if I'm wrong, but does'nt the SR-71 exclusivaly fly with his Ramjets at this speed???

GD

[luc]

Hi Sadmemories20,
Aerodynamics is the most important factor.
Airframe, materials,design -everything must work.
A huge engine will get you there.
"...without making any special arrangement in the exit of the turbojet engines"
Variable nozzles, reheat/afterburner etc - that will just get you there quicker.
Modern passenger jets have the potential to do it ( eg:727 - well not that modern - see TWA 841. DC-8-42 on August 21, 1961 .A China Air 747 also did it over the Pacific).
However it's not feasble due to fuel consumption,economics,airframe problems,people
complaining about sonic booms, and the ever present....
"When you go supersonic you open a bad ass can of nasty whoopass worms."

Very good description of the problems and what needs to be done ...

The YF22 raptor is also a good example as this one achieves steady cruise above the sound barrier, so I guess it can be done.

The engine is not the problem if you can make it produce the desired exhaust velocity. But on the other side, the biggest problems will turn to be the inlet air speed and shockwaves at this speed, which brings you back to your airframe like expressed above.

If it can't breed ... It can't push ... Unless you have a rocket.

I Love this one ("When you go supersonic you open a bad ass can of nasty whoopass worms.") ... He he he ...

Hooo ... By the way ... Conception GLC never did such combination and trials ... Just a hint ...

GD