threaded SCH 40 Pipe Pulsejet

Moderator: Mike Everman

Post Reply
chachie1226
Posts: 1
Joined: Fri Feb 24, 2006 7:55 pm
Antipspambot question: 0
Location: CA

threaded SCH 40 Pipe Pulsejet

Post by chachie1226 » Fri Feb 24, 2006 8:01 pm

hi all, i built a pipewood engine for a science fair project. I got it to run with a constant flow of air and got it to run for like 2 sec without air, and thats it. anyone know whats wrong?
Attachments
IMG_1415.JPG
(1.65 MiB) Downloaded 333 times

steve
Posts: 1029
Joined: Sun Jun 06, 2004 12:29 am
Antipspambot question: 0
Location: Clinton Conneticut / Melbourne Flordia
Contact:

re: threaded SCH 40 Pipe Pulsejet

Post by steve » Sun Feb 26, 2006 7:17 pm

probably not enough fuel
Image

attache'
Posts: 9
Joined: Fri Sep 30, 2005 1:49 am
Antipspambot question: 0
Location: Delaware, USA
Contact:

re: threaded SCH 40 Pipe Pulsejet

Post by attache' » Tue Feb 28, 2006 12:50 am

How are you suppling the fuel, and what are using to start it (spark/flame, compressed air/vacuum)? ... i got one of these running a few months ago for high school senior research. I'll try to upload some pics by saturday the 5th
Mathematically, it can be described in terms of extra dimensions that are rather peculiar. Whereas ordinary space and time dimensions are described by ordinary numbers, which have the property that they commute.

attache'
Posts: 9
Joined: Fri Sep 30, 2005 1:49 am
Antipspambot question: 0
Location: Delaware, USA
Contact:

re: threaded SCH 40 Pipe Pulsejet

Post by attache' » Wed Mar 01, 2006 12:23 am

Even after correcting the chamber size, i couldn't get it to work, but i put in a fuel injector using brakeline fittings threaded through the chamber to use propane. Normal USA propane valves, after the regulator, thread in to the brake line perfectly.
Not to scale...
Attachments
injector.JPG
sch40
injector.JPG (11.86 KiB) Viewed 3258 times
Mathematically, it can be described in terms of extra dimensions that are rather peculiar. Whereas ordinary space and time dimensions are described by ordinary numbers, which have the property that they commute.

attache'
Posts: 9
Joined: Fri Sep 30, 2005 1:49 am
Antipspambot question: 0
Location: Delaware, USA
Contact:

Re: re: threaded SCH 40 Pipe Pulsejet

Post by attache' » Wed Mar 01, 2006 3:47 am

Ben wrote:Your fueling rig may be taking up too much of the volume of the chamber or area of the intake.
I wrote:Not to scale
1/8 inch after a reducer. .19 out of .63 area (2-d) taken up, also I have the intake the same size as the tail pipe. solved the problem of me finding a reducer 2 to 3/4. Plus the chamber length is a 1/2 in. longer in length from the edited length in the other forum. Sorry bad picture.
Mathematically, it can be described in terms of extra dimensions that are rather peculiar. Whereas ordinary space and time dimensions are described by ordinary numbers, which have the property that they commute.

Mike Everman
Posts: 4926
Joined: Fri Oct 31, 2003 7:25 am
Antipspambot question: 0
Location: santa barbara, CA
Contact:

re: threaded SCH 40 Pipe Pulsejet

Post by Mike Everman » Wed Mar 01, 2006 5:03 am

The intake looks shorter than plan. If you've made it 1" pipe, it may need to be a bit longer still, which changes other lengths, etc. Simple rules are meant to fall, but like Ben says, really give what already works a fair shot.

Preserving an L/D ratio of 6.25 or so on the intake may be more important than the intake length being 1/7 the over-all, but I haven't tried the 1" intake.

The pipe fittings are so crappy for flow, really, it's the main reason to go with a straight pipe and a smaller diameter intake; it's the most forgiving layout.
Mike
__________________________
Follow my technical science blog at: http://mikeeverman.com/
Get alerts for the above on twitter at: http://twitter.com/mikeeverman

attache'
Posts: 9
Joined: Fri Sep 30, 2005 1:49 am
Antipspambot question: 0
Location: Delaware, USA
Contact:

re: threaded SCH 40 Pipe Pulsejet

Post by attache' » Wed Mar 01, 2006 9:01 pm

I'm curious. Pulsejets seem to always be discussed in leignth (maintaining the ratios); Why not volume? We are expanding gas in 3 dimensions. second, how have these ratios come about: mathmatical/trial and error? I have always use trial and error.
Mathematically, it can be described in terms of extra dimensions that are rather peculiar. Whereas ordinary space and time dimensions are described by ordinary numbers, which have the property that they commute.

Bruno Ogorelec
Posts: 3542
Joined: Sat Oct 04, 2003 7:31 am
Antipspambot question: 0
Location: Zagreb, Croatia

Re: re: threaded SCH 40 Pipe Pulsejet

Post by Bruno Ogorelec » Thu Mar 02, 2006 12:27 am

attache' wrote:I'm curious. Pulsejets seem to always be discussed in leignth (maintaining the ratios); Why not volume? We are expanding gas in 3 dimensions. second, how have these ratios come about: mathmatical/trial and error? I have always use trial and error.
To put it simply (perhaps too simply), pulsejets are acoustical devices. Their functioning is to a large extent governed by the laws of acoustics. They work best when the gases inside display resonant behavior, meaning that their pulsations resemble a standing wave pattern. For that to happen, the shocks (places of pressure transition) have to be at certain distances from each other. That is why lengths are usually more important than sections and volumes.

attache'
Posts: 9
Joined: Fri Sep 30, 2005 1:49 am
Antipspambot question: 0
Location: Delaware, USA
Contact:

re: threaded SCH 40 Pipe Pulsejet

Post by attache' » Thu Mar 02, 2006 11:05 pm

True. Organ tuners becoming rocket scientists, interesting. I am on the board of directors for a theator organ society. Never saw the parallel. Thanks
Mathematically, it can be described in terms of extra dimensions that are rather peculiar. Whereas ordinary space and time dimensions are described by ordinary numbers, which have the property that they commute.

Post Reply