Kriz Pulso 3

[nate_s_gr8]

Hello,
did anyone ever build or seen a running Kriz Pulso 3. I mean this one http://www.youtube.com/watch?v=gJc2VadsHIg
This is the only vid i´ve found and in another Forum i´ve found some pics but both Pulso3 doesn´t run.

Can somebody help me i´ve had start to build this thing and i hope it is runing.

René

[metiz]

I think the duct on that thing was to short for stable running. I'm not sure about this, if anyone wants to chip in. Untill you know for sure I suggest you put your build on hold for now

[nate_s_gr8]

Damn , the half of the parts i need are finished. I´ve wondered a lot, because the Kriz Pulsos are the only one in this short style.
Now i know why they are.

[Johansson]

I think I remember that Manolo built one of these a while ago, he posted some pics of it producing flames during a start test but I don´t think he ever got it to run properly.

[nate_s_gr8]

I don´t understand that plans of that pulso on the net, although it doesn´t run.

whatever...i try to build another one.

thanks

[Johansson]

Try to lenghten the tailpipe some, that might be all that is needed to make it a runner.

[metiz]

Yes I agree. In the video you posted a link to it's pretty damn close to running. A tailpipe extension might very well solve the problem.

[nate_s_gr8]

ok mayybe i should try to lengthen it up...if i get some results i´ll post it here

[Vilkas]

Hi, everybody!
I have faced the same problem with Pulso-3. I didn't run. Although I have added a piece of tube, making it simillar to a standard valved PJ (like Pulso-1). As a result of test firing I've found to things - it didn't run without and with additional tube and it backfired through the valve grid demaging valve plates. I suppose the prblem is somehow connected with the valve grid design. Accordind to Borodin (Бородин В.А.: Пульсирующие воздушно-реактивные двигатели для летающих моделей самолетов, 1968) a pulse jet of such a shape is possible (although it is a bit longer than original Pulse-3, according to a picture in Borodin's book). Somehow, I suppose frequency of pulsations in a combustion chamber doesn't match with an operating frequency of valve system. Has anybody any other ideas? Or has anybody made this engine operational?

[Mark]

While perhaps not an absolute, I would think many small reeds would have a faster response time over the larger petal valves. The jet being so proportionately short, the reeds can't afford to dampen too much feedback by not closing fast enough, and smaller reeds might also help in mixing the fuel/air ratio. Recall the Dyna-jet has ten petals that swing open and closed ~220 times a second. And in one article I read it said some fuel/air backflow still sneaks by the reeds an inch or so before being reingested by the engine. You're not getting that intimate mixing with those jumbo reeds. Look at the Schmidt tube, that thing is loaded with tiny reeds.
I once tried some snowmobile reeds, a pyramid of 4 petals in a 2.5 inch diameter straight duct about 30 inches long. While I got some strong barks occasionally with forced air and some impressive backfiring sounds, I couldn't get it to sustain. Maybe I wasn't getting good fuel/air mixing or maybe a straight duct is just so slippery, you've got to have your reeds close the gate very suddenly. Smaller reeds might have helped create turbulence as well as having a faster response time.
Also a retainer might help by limiting the reeds from swinging open too far or a small dish in front of the reeds would protect them from heat as well as create some turbulence as the fuel/air skirts by around it. Tharratt used an annular dish in one of his designs.

[Mark]

I haven't seen the Borodin book, but it sounds like a good book to read, if only it were in English. Is it kind of like this book?
http://www.bell-everman.com/kazoojet_fi ... 20Ruso.pdf

[gary]

A bit late to the party here but I think this 6 inch pulse-jet is a knock-off from the 1951 GE 6 inch ramjet. They both measure 29 inches in length and use the same (approximate) shape. That GE 3R-1 ramjet was reported to resonate at certain fuel levels by the test engineer, a fellow named Igor Bensen no less. The GE jet used an aluminum shell and an inconel combustor inside to produce a claimed 50 HP at max velocity (1000 ft/sec) though it is a subsonic design. The GE ramjets later showed up on Igor Bensen's "Midjet" helicopter as a military project.

So it would seem that someone has attempted to make that early jet into a mostly resonating device via the reed valves likely for helicopter blade tip applications rather than test stand or skate board uses.

As has been mentioned the reed valves don't appear to be closely tuned to the tube frequency. Shorter and more reeds would be a step in the right direction. Perhaps even reversing that wed-shape reed frame to point up-stream with the reeds located inside and anchored at the upstream end.

The fire hazzard from that carburetor type fuel system (see manolo's video) would be reduced using a fuel injection inside the combustor. The GE jet used FI of course.

I will attempt to add a picture of this stuff but have yet to learn how to...


Gary

[Vilkas]

Just in time, Gary! I was just thinking to resume work on this engine. So any advice or idea is acceptable. Thanks!

[gary]

Hello Vilkas,
Attached below hopefully is a picture of the US Naval Research Laboratory Tech Pamplet 4536 extract Survey of Static Performance of Pulsejet Engines. These are all valved pulsejets reported by Gary Burgner ca. 1968. Note the great variation of proportions for these jets. All except the Dynajet appear to be the Argus-type flap valve intake.

Gary Burgner once mentioned that the max limit of the petal valve size was about 6 inches. I'm sure others here have discovered that phenomenon. Some experimenters have altered petal valve resonant frequency using doubled reeds or even 1½ reeds stacked together. This trick could be tested with your current reed cage design.

However... my thoughts are to reverse the wedge-shape reed "cage" to point upstream in the intake. About 1 inch will protrude from the cowl. The 1/2 length reeds (2x as many) would be fastened at the inside of the re-designed cage perhaps even as Argus flapper type valves.

An interior fuel injection spray would be directed up-stream at a baffel aft of this reed assembly rather like the 90mm Ollarius p-jets and clones. This produces a fan-like radial spray pattern.

Pulsejets to my thinking should resonate like a musical instrument powered by gasoline !!!! They should resonate with an intake airflow rather like a saxophone. The long exhaust tube (jet tube) helps boost the inflow but ram air intake also powers the system. This is notceable in the short p-jets used on some helicopters rotors years ago.

Did you notice how the large reed valves hung open when Manolo introduced air flow into his 6 inch p-jet in the video ??? Those reeds didn't appear to resonate. Bad trend !!!!

My p-jet interest centers on helicopter applications which are a very dynamic environment.

Gary in AZ

[Vilkas]

Thank You, Gary.
We'll try to work on it once again. First of all we will use internal fuel injector - just behind the valve unit. If it would't work - the idea of "inverted" valve unit is to be tested. By the way - any more information on PV-8 engine available?