Search found 1743 matches

by PyroJoe
Mon Apr 23, 2012 2:10 pm
Forum: Valveless pulsejet forum
Topic: PyroJoes Recipe for Beginners
Replies: 209
Views: 1711562

Re: PyroJoes Recipe for Beginners

From what I've read, speed of sound does increase as the temperature of a gas is increased. Also the gas composition can affect the speed. Even if the gas speed of the exhaust is twice as fast as the intake, you can see that the intake will allow the escape long before the exhaust reaches the end of...
by PyroJoe
Fri Apr 20, 2012 8:33 pm
Forum: Valveless pulsejet forum
Topic: PyroJoes Recipe for Beginners
Replies: 209
Views: 1711562

Re: PyroJoes Recipe for Beginners

For something like a sphere is more difficult. It would require the transition from chamber to tail to have some radius to it, so the flow would be biased to the tail without congestion(blue). The intake/chamber port would need to be sharp on the inside to aid in valving (red).
by PyroJoe
Fri Apr 20, 2012 8:16 pm
Forum: Valveless pulsejet forum
Topic: PyroJoes Recipe for Beginners
Replies: 209
Views: 1711562

Re: PyroJoes Recipe for Beginners

Occasionally I have reported of a side wall intake leak, This is when the intake is in close proximity to the sidewall of the chamber, and what is happening is part of the intake is flowing freely without congestion. A few engines wont even sustain operation with this type of leak. Although a side l...
by PyroJoe
Fri Apr 20, 2012 8:02 pm
Forum: Valveless pulsejet forum
Topic: PyroJoes Recipe for Beginners
Replies: 209
Views: 1711562

Re: PyroJoes Recipe for Beginners

Now with the intake port having a sharp edge it creates congestion in the intake/head port, while the port leading into the tail is at a very low angle. This creates a bias for the most of the flow created by the deflagration event to flow through the tail port. The density of the gas trapped in the...
by PyroJoe
Fri Apr 20, 2012 7:41 pm
Forum: Valveless pulsejet forum
Topic: PyroJoes Recipe for Beginners
Replies: 209
Views: 1711562

Re: PyroJoes Recipe for Beginners

Eventually the intake flow will stop when events have changed the parameters at the chamber port.
by PyroJoe
Fri Apr 20, 2012 7:32 pm
Forum: Valveless pulsejet forum
Topic: PyroJoes Recipe for Beginners
Replies: 209
Views: 1711562

Re: PyroJoes Recipe for Beginners

I somewhat have accepted the idea that ignition occurs typically in the back of the engine and works its way forward, probably with a slight pressure wave ahead of it. The incoming air charge starts to pile up against the forward moving front until intake flow slows.
by PyroJoe
Fri Apr 20, 2012 7:25 pm
Forum: Valveless pulsejet forum
Topic: PyroJoes Recipe for Beginners
Replies: 209
Views: 1711562

Re: PyroJoes Recipe for Beginners

Eventually the tail will start to achieve a flow into the chamber, not sure of when or if this is near accurate. The long slow cone allows the in flow from the tailpipe to enter without obstruction, very smoothly.
by PyroJoe
Fri Apr 20, 2012 6:52 pm
Forum: Valveless pulsejet forum
Topic: PyroJoes Recipe for Beginners
Replies: 209
Views: 1711562

Re: PyroJoes Recipe for Beginners

After a good in flow at the entrance has been achieved the flow will enter into the combustion chamber. Here (marked by red circles)I like to use a sharp edge that allows the intake flow to cleanly shear away from the intake port and continue deep into the chamber. Notice here that the intake air te...
by PyroJoe
Fri Apr 20, 2012 6:39 pm
Forum: Valveless pulsejet forum
Topic: PyroJoes Recipe for Beginners
Replies: 209
Views: 1711562

Re: PyroJoes Recipe for Beginners

If we look at a intake that has a gradual radius that forces the side air to enter at a low angle, then the flow can proceed without much resistance or congestion. Nice and smooth. This is why most members on the forum will instruct to "flare" the intake pipe to avoid problems during in flow into th...
by PyroJoe
Fri Apr 20, 2012 6:25 pm
Forum: Valveless pulsejet forum
Topic: PyroJoes Recipe for Beginners
Replies: 209
Views: 1711562

Re: PyroJoes Recipe for Beginners

If an intake port or pipe has a sharp edge, it creates a condition in that some of the air around the port has to enter the port at an angle that is very near perpendicular to the axis of the port (shown here in red). The inertia of the gas doesn't allow the gas to quickly turn the corner/edge, and ...
by PyroJoe
Fri Apr 20, 2012 6:00 pm
Forum: Valveless pulsejet forum
Topic: PyroJoes Recipe for Beginners
Replies: 209
Views: 1711562

Re: PyroJoes Recipe for Beginners

Over the next few posts I will attempt to explain "aerodynamic valving". This is my own thoughts on the matter and not comprehensive of all designs. As seen in the Lockwoods and many other designs, valveless pulse jets can run without much need for the effect. On occasion I violate the concept mysel...
by PyroJoe
Thu Apr 19, 2012 2:53 pm
Forum: Off topic forum
Topic: Mike Everman, Top Engineer?? Doubt it!
Replies: 2
Views: 2202

Re: Mike Everman, Top Engineer?? Doubt it!

Ha, watched that one awhile back, man thats a kick.
Hope you get in and do well! Know you will have at least one fan routing for ya. :D
by PyroJoe
Thu Apr 19, 2012 2:21 pm
Forum: Valveless pulsejet forum
Topic: Please put your "I am new and need help" question here.
Replies: 374
Views: 1758761

Re: Please put your "I am new and need help" question here.

Thats very close for TLAR method, you must have a good calibration of your eye. :D There are some details of aerodynamic valving that will help in ease of starting and fill ratio. A sphere may be a little tough to sweep the entire volume of residual exhaust gas. I will post some basic illustrations ...
by PyroJoe
Thu Apr 19, 2012 1:28 pm
Forum: Valveless pulsejet forum
Topic: Please put your "I am new and need help" question here.
Replies: 374
Views: 1758761

Re: Please put your "I am new and need help" question here.

First I converted liters to cubic inches. 5 liters=305.12 cubic inches Then I scaled the recipe CC (the one with the cone section) to have a mass property volume of 305.12, this gave the diameter of the tail. Just for kicks I seperated the cone and the cylinder to see how their volumes compare. The ...
by PyroJoe
Wed Apr 18, 2012 6:43 pm
Forum: Valveless pulsejet forum
Topic: More free plans: 40 pound Chinese
Replies: 182
Views: 716841

Re: More free plans: 40 pound Chinese

Any luck with this one yet? It looked a little low on fuel supply. I used those type tanks and on that size engine, if you full open the valve for more than about 100 seconds the fuel pressure will drop off rapidly.

Try to preheat the tank up near 100F if possible before each attempt.