Multiple inlets

[GRIM]

Inlets 7 X 10 mm id

It is curious to see the combustión through so many holes , ha,

Will post more photos with it running , time!!, where does all the time go these days ¿??

[Mike Everman]

Bwaha ha ha
That's cool. Most I've done is four. Running vid would be great.

[Ghrey]

Yes that is a must see.

Was tuning an issue?


Cheers!

[Irvine.J]

Gatling would be proud haha

[Graham C. Williams]

Good Morning.
'Kentfield' et al, did some work and made some comments concerning multiple intakes. Later 'Bill' duplicated this work, I think his results are on the forum somewhere?

Graham.

[GRIM]

Thanks to all for the replies , will check out ¨Bill¨ and Kentfield, Heres a picture and two (shakey) vids ,

There is a reason for the two vids, would someone be so kind as to confirm frequency for me, according to my program the frequency is higher in the second vid, (the injector was a little deeper ),

I think the inlets should be longer , only one way to find out I guess,

I will post a pdf of the dims if anyone is interested

All fun

[larry cottrill]

Absolutely great stuff! What is your fuel pipe like? I mean, does it just empty downstream in the center pipe, or does it "project" fuel outward inside the chamber, to cover the outer intakes?

Really nice one, man!

L Cottrill

[Viv]

Hi Grim

What a superb little engine, well done

Viv

[GRIM]

Hey thanks guys , heres the pdf ,

The injector is one of my 3 point deals with 3 #16 hypodermic needles silver soldered into the end then bent around at near to 90degrees so they ¨spray¨ out over the outer inlets , it is not nearly as nice as the drawing shows , ha, will try to get a pic,

Also quite surprising that it survives there in the cc , but I have done similar things before , as long as there is a good gas flow I believe it provides sufficient cooling to avoid melt down,

I am quite pleased with this one , just feel it would work better with longer inlets , will give it a try , might even make a stainless one just for the hell of it ,

[hinote]

SRL did this hovercraft project some years ago ('02 I think) and powered it with multi-inlet PJ's.

Here's a photo of that project.

[hinote]

There's a lot of material on this site about the Kentfield and similar efforts, using a 4-tube inlet array. Use the search engine to find related material!

I believe that 4 intakes may be optimum; my theory is that the wetted area of increasing tube arrays dilutes any advantage they would otherwise have.

The Kentfield is a proven design, but not perfect. My experience with it as a first effort in valveless PJ's shows that it's easy to start and run. The tail meg is quite long and eliminates the possibility of inserting the desirable ubend to point both ends in the right direction. Fueling with propane is a no-brainer, with the use of a centrally located injector squirting radially into the intake flow.

M has supplied dimensions for an improved version, with greater power and better TSFC. I believe he also offered to provide specs for a unit with ubend capability.

As a teaser I'm attaching Larry C.'s excellent posterized images of my Kentfield project running on liquid fuel and equipped with recuperators. Old news, BTW

[GRIM]

Thanks bill , thats some great feedback , i am just having some fun with this little engine , but it is good to have some information to base a possible next step upon,

the hovercraft is cool , it is clear that there are exhaust augmentors , are they tiny inlet augmentors in the photo?
if so i wonder how efficient they are ,

thanks
again

joe

[Mike Everman]

I think those are non augmenting u-bent recouperators, though even at the same diameter as the intake, it can give a bit of augmentation, as a cold air plug is in there alternately. Oh, I see now that there is also augmentors beyond that.
I love that video of your motor!
Is there a throttle setting that gets you a blue burn? It's getting pretty involved down the tail. I like it. You going to get a thrust off of it?

[GRIM]

Hi Mike
No currently very little throttle range, no nice blue flames , except at start ,and I agree things are getting a little warm down the tail ,

looking at the ratios, seems to me that the inlets are too short and the tail is too long , amazing it runs at all really,

I intend to try some mods , then see if i cant get a thrust reading, will keep all informed of progress,

[Charles]

Hey there,

That's an awesome engine, one question I do have is about the barrels themselves, as they protrude out the front? do they come flush with where their all joined too or they do they protrude inwards as well?

See I was thinking if they came flush, they would allow more blow-through? but maybe if they were set-back into the inner chamber they might stop some of the burnt force from exiting where the intake is coming in.
That's an awesome engine man, would love to hear about the overall what got you thinking along these lines, simply awesome

*Does anyone know if an explosion acts the same way a flame does and that it would be hollow?

I have seen a resonant jet patent which kinda did the same with the pipes as inlets, I'll see if I can dig it out for you

All the best,
Charlie