supersonic valveless pulsejet

[ganuganu]

experts are familiar how to make the calculations for making a normal valveless pulsejet producing thrust of 700lbs of thrust,but how can we make a valveless pulsejet engine which can runs at a speed of mach 1(speed of sound)..which means achieving a speed of 343m/s = 1236kmph..

has anyone achieved in making it in olden days..

[ganuganu]

why no answers??????......

[metiz]

don't Take this as the absolute truth because I don't know for sure:

No normal pulse-jet will ever be capable of reaching =>mach 1. The pj gasses will never go as fast as the speed of sound and I think there are some combustion issues if you did somehow manage to get up up to mach 1.

Anyone want to chip in here?

[ganuganu]

The pj gasses will never go as fast as the speed of sound and I think there are some combustion issues if you did somehow manage to get up up to mach 1.

Anyone want to chip in here?

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....

so if we make the special arrangements made in sonic turbojets engines in our pulsejet engines..can we achieve the speed

[metiz]

what kind of arangements did you have in mind? no normal pj will expell gasses @ the speed of sound under any circomstances.

[ganuganu]

what kind of arangements did you have in mind?

to achieve sonic speed in jet engines scientists modify the diameter and length of the nozzle designs,and also they use an vibrator arrangement so that we could increase the downstream pressure and decrease the upstream pressure..so if down stream pressure increases the velocity of the exit gas can be increased...by this way we could achieve sonic speed in pulsejet..

[metiz]

Noozle design is crucial for a pulse-jet engine. It helps govern the engine. You can't just modify it. If you do it changes the dynamics of the engine. You can only go so far before the engine dies. Then you'd have to modify the rest of the engine to compensate, killing off any effect

[Mark]

Maybe once you got up past the speed of sound, it would be better to just ramjet. I recall Foa saying the line of demarcation between a valveless pulsejet and ramjet is blurred. Subsonic ramjets benefit from pulsating combustion his book said. Of course a ramjet doesn't start standing still. Somewhere in there is a compromise you make.

[metiz]

Yeah, slap a ramjet behind a pj, that might get things supersonic
not a solution to the problem but a way to achieve the end results

[ganuganu]

Yeah, slap a ramjet behind a pj, that might get things supersonic
not a solution to the problem but a way to achieve the end results

take a look at this sir,source from wikipedia..

"The valveless pulsejet's first widespread use was the Dutch drone Aviolanda AT-21[9] A properly designed valveless engine will excel in flight; as it does not have valves, ram air pressure from traveling at high speed does not cause the engine to stop running like a valved engine. They can achieve higher top speeds, with some advanced designs being capable of operating at Mach .7 or possibly higher."

[metiz]

Didn't know about the Dutch drone, but it still suggest a peak of not a lot higher then mach 0.7

[ganuganu]

by using pulsejet alone we could achieve 0.7 mach number,now we will make a prototype i.e we will attach a ramjet to it and make mach 0.7 into 1..now it is possible right..

[metiz]

I think a pj would stop being effective at mach 0.7+ speeds. I think that if you have a stationairy setup, the airflow may reach mach 1+, however, putting a ramjet behind a pulse-jet in flight may be useless. A pulse-jet can go up to mach 0.7, anything above and the pulse-jet will be pointless. So if you want to achieve supersonic flight you may need to make a plane with dual propulsion. A pulse-jet to reach mach .7 and a ramjet to take it over from there. A properly build ramjet would be capable of reaching maybe mach 2.5

[ganuganu]

so you are saying like the combination used in blackbird(turbojet/ramjet)..

[metiz]

hmm something like that. Only not a hybrid (It's possible: Conception GLC made a system like that I think) but 2 seperate engines. one to get up to speed (pj) and one to take over from there (ramjet)