premixed fuel chamber.

[SpudFarm]

I can't get involved into your discussions before I have first hand experience so I will rather ask you guys to give me some opinions on my valve design.

I want to keep the design as simple as possible but still effective. I want it to be quick to fuel and eventually vent.
I have been thinking about size for the valve for a while and I am stuck between 2" and 3" tee fitting housings. I want to use a golf ball sized barrel so it has to have some flow. It is going to be used at 5 to 10x mixes.

My problem is that I don't know how to calculate opening pressure and that sort of stuff yet.

What I want is a 2" housing but I don't know if that is possible with a 1.5" seat. If possible I will use a 1.75" seat but the problem is that I have no clue.

Keep in mind that this diagram is not done. Fueling ports ETC is not added yet.

Sorry about my crappy explanation but this is quite hard to explain for some reason.

[SpudBlaster15]

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[SpudFarm]

Thanks for your help!

As I am really bad when it comes to math I will have to try and use the calculations I think of as logical and get a equation that you can approve.
What I am about to do is to find the surface area (roughly as I don't have exact measurements of the parts I will use) and find the force acting on the piston.

1.5" seat:
1.5"= 3,81cm 1,905*1,905*3,14= 11,395cm2 surface area on seat.
2" piston:
2"= 5.08cm 2,54*2,54*3,14= 20,258cm2 surface area on entire piston.

So subtracting the area of the seat from the piston itself gives me 8,863cm2 surface area on the "ring" that the chamber pressure acts on.

I am pretty certain the above is correct but from here on out I am completely in the dark. I will play around and see where it leeds me.

Lets just start off with a rough 11x mix assuming a pre ignition pressure of 10bars.
That will lead to those loads:
Seat load: 113,95kg
Entire 2" piston load: 202,58kg
Ring load: 88,63kg
From here I am guessing that I will have to raise the pressure (in form of combustion pressure) in front of the piston (between the seat seal and the seal against the housing) to the point where the load on the "ring" is higher then the 113,95kg acting on the seat.

Once again I am in the dark and only doing math out from what I find logical.

I took the 113,95kg acting on the seat and divided it to the 88,63kg acting on the "ring" and got a ratio of 1,285. I then took the pressure of 10bar and multiplied it by the ratio between the seat and the ring and got a pressure of 12,85bar.
Now I want to check if there are any bond between those numbers so I find the force acting on the "ring" when subjected to 12.85bar and that turned out to be 113,889kg witch is pretty close to the force acting on the seat. The deviation is caused by me shorting down to two decimals.

What this seems to tell me is that this valve will open at slightly above 12,85bar.

I don't know if this makes any sense to you at all but if I am right I will be suprised. I would think that the load on the seat would simply rise as the combustion rises the pressure. I hope that you mention something about pilot pressure ETC that causes everything to make more sense to me.

I can try to write a shorter version of this if you want me to, this is just a "blueprint" to make sure I got it right.

[SpudBlaster15]

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[SpudFarm]

I am getting closer here, but there are still bits I need to place right.

If I got it right now you have a perfect seal around the piston in the housing. Prior to fueling you pressurize the pilot chamber to a pressure higher then the pre ignition pressure to hold it sealed, then fuel directly into the chamber?
Then when the pressure infront of the piston gets higher then the pressure behind it, it will actually crack the valve?

I thought the piston would have to be forced from the barrel port and thus limiting you to using a port with less than half the surface area of your piston itself.

When you get time you could explain it in more depth. It is kind of hard to get it at first.

Thanks for your help again.

[SpudBlaster15]

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[SpudFarm]

Got it! I am not entierly done reading about it but I think I know enough to start designing the valve to more detail.

I will write more once I have another diagram.

Edit: I made a diagram where I made the seat incredibly close to the housing diameter.
I just want to ask if this design could work. No calculations, just your judgement based on the looks of it.
If you tell me that this would work it will make the rest of the designing much easier.

[SpudBlaster15]

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[SpudFarm]

Then I hope to build this as soon as possible.

I will try to get the next diagram exactly to scale, I just have to find the dimensions of the tee and the seat.

I wasn't using paint for this one, I used something called "EMachineShop"
It allows me to make each part out of different materials and then turn it into a 3d model if I want to.
Then the program can calculate the cost for those parts made on CNC machines.
I recommend it!