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Post by hyperdrive on Apr 21, 2015 9:50:19 GMT -5
I am building a valve less pulse jet and have it operating ok on propane but I am ready to switch it over to a liquid fuel such as gasoline. I would like to tap into a pressure region with a very small line and run that line to a small pressure storage tank mounted on the chassis. Within that small pressure tank I would like to have a pressure transducer that would shut the fuel pump off if the pressure drops below a certain threshold, much like an oil sending unit does when your oil pressure gets too low on an automobile engine. This would be a crude way to tell the system that the pulse jet is running. So I have three questions.
A) Will a very small line tapped somewhere in the combustion area interfere with the cycling of the PJ?
B) Given the way the pulse jet operates would the pressure tank be in danger of collecting the right amount of un burnt fuel and oxygen as to cause the pressure tank to explode?
C) And last if the answers to A & B warrant such a device where would be the ideal place to tap the pressure?
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Post by britishrocket on Apr 23, 2015 9:52:09 GMT -5
Welcome Hyperdrive,
I don't know the answers to your questions, but I'd like to congratulate you on an absolutely fantastic build. Where in the world are you located?
All the best,
Carl.
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Post by hyperdrive on Apr 23, 2015 10:01:53 GMT -5
Thanks Carl I am from a little town in the Piney Woods of East Texas called Lovelady. My nearest neighbor is a mile away, no noise restrictions here  |
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gidge348
Senior Member
Joined: September 2010
Posts: 426 
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Post by gidge348 on Apr 23, 2015 22:49:06 GMT -5
Hello Hyperdrive, great looking project, sorry I cant answer your question but it may be useful to place a serried of bungs down the length of the engine and do some experiments? I for one would be interested in the results You may find an area that provides the best instantaneous pressure but as it cools in the tank the pressure may drop? Another area with a lower instantaneous pressure and lower temp may give you the best result? Another thing to bear in mind since a pulse jet .....pulses.... and pressure will vary wildly so you will probably need some type of reed valve to keep the pressure going in one direction. As a thought I have seen a lot of cars as part of EGR system they have a small reed block that could probably be modified to do the trick?  Cheers Ian... |
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metiz
Senior Member
Joined: April 2011
Posts: 297
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Post by metiz on Apr 25, 2015 18:56:55 GMT -5
The best place for such a tap would be at the transision point of the tailcone to the tailpipe. If I remember correctly, there's a pressure antinode there. Don't mess with the combustion chamber too much. Also don't forget that this engine cycles at +200hz so your system will have to react realy fast. If you try to build in a timer, also don't forget that the cycle time of a pulse-jet will varry throughout its opperation. Not by that much, +-5hz or something, but enough to mess up your finely tuned system.
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