injectors

[haaken]

Does anyone have experience using stainless steel tube "Rails" inside the combustion chamber on a pulsejet?

I am planning to use it to inject liquid fuel. I suspect the tubes will get hot enough to waporise almoust any type of fuel, but im worried that they may melt due to the extreme heat. They may be cooled enogh by the incoming airstream during the intake cycle .

Altso notice the turbulators on my drawings, i hope they will improve fuel/air mixing some.
Opinions and comments are welcome!

HÃ¥ken Hveem
Norway

[larry cottrill]

Does anyone have experience using stainless steel tube "Rails" inside the combustion chamber on a pulsejet?

I am planning to use it to inject liquid fuel. I suspect the tubes will get hot enough to waporise almoust any type of fuel, but im worried that they may melt due to the extreme heat. They may be cooled enogh by the incoming airstream during the intake cycle .

Altso notice the turbulators on my drawings, i hope they will improve fuel/air mixing some.
Opinions and comments are welcome!

HÃ¥ken Hveem
Norway

HÃ¥ken -

I have always liked the idea of creating a little drag and turbulence just aft of the valves. I used an idea similar to this in my Cyclodyne(TM) design [which is not a pulsejet] to achieve a similar effect.

I think that where you have them located, they would be cooled adequately to keep the stainless from being badly eroded. Stainless does not hold up well if fully immersed in the combustion gases. See my article on destructive tests in the last issue of jetZILLA:
http://www.jetzilla.com/jetZilla.html#Article_1

However, as I said, I think the location you have indicated should be cooled well enough to work all right. Of course, only experimentation will determine the answer for sure. But, I think this is the right place to create a bit of beneficial turbulence in a valved design.

L Cottrill

[Pieter van Boven]

Haaken,

In a previous post about your design you told us that the combustion-chamber diameter will be 185mm. This is big but I don't think you need more than 1 fuel-injector if you use injected fuel. This would also be an advantage because you could make the injector a part of the valve grid and the pressure on one injector will be higher than on eight. (much easier if you want to replace or clean the injectors) I also think you need a pump. Your injectors will get hot but you have to start the engine first when it is cold.
The turbulators are usefull to protect the valves from the heat.

Pieter.

[Pieter van Boven]

Haaken,

I don't know if you are allready building your jet but I think you could get a better valve area/comb.chamber diameterproportion. Take a look at the sketch I made. It is a 280mm diameter fitted with argus valves. i think you can get more valve area.

Pieter.

[haaken]

Haaken,

In a previous post about your design you told us that the combustion-chamber diameter will be 185mm. This is big but I don't think you need more than 1 fuel-injector if you use injected fuel. This would also be an advantage because you could make the injector a part of the valve grid and the pressure on one injector will be higher than on eight. (much easier if you want to replace or clean the injectors) I also think you need a pump. Your injectors will get hot but you have to start the engine first when it is cold.
The turbulators are usefull to protect the valves from the heat.

Pieter.

I know that it needs too be started on propane to heat up the injectors.
They work like fuel vaporisers on kerosene owens/blowtorch's

I dont think i need to use a pump, i will just keep the fuel tanks bottom higher than the injectors, an gravity vill do the rest.

By the way, i have calculated the effective valve intake area to be 15300MM2 ( scuare milimeters ) , the holes in the front plate are 4787,6832
eatch. I think it should be ok.

All my dravings are already sendt to a company that cuts steel with laser.

[Hank]

I dont think i need to use a pump, i will just keep the fuel tanks bottom higher than the injectors, an gravity vill do the rest.

Haaken, You wish to inject fuel into an occilating column of expanding and contracting gases. Gravity alone will not provide the pressure necessary to feed the fuel unless you wish to have your tanks suspended a great height above the engine.. Consider a pressurized fuel tank. Argus engines used plywood spheres rated to hold up under a pressure of 150 bar. Hank

[haaken]

I dont think i need to use a pump, i will just keep the fuel tanks bottom higher than the injectors, an gravity vill do the rest.

Haaken, You wish to inject fuel into an occilating column of expanding and contracting gases. Gravity alone will not provide the pressure necessary to feed the fuel unless you wish to have your tanks suspended a great height above the engine.. Consider a pressurized fuel tank. Argus engines used plywood spheres rated to hold up under a pressure of 150 bar. Hank

Ok, i will see i can find something useful.