www.pulse-jets.com

Ok, I'm not sure if this should actually be over in the valved pulsejet part of the forum or not, and maybe it's already been covered. Tesla, way, way back in the day, came up with this ...flow diode. Theoretically would allow flow in one direction and restrict flow in the other direction. I came across a page

http://www.me.psu.edu/me415/fall04/APC2/

at Penn State mechanical engineering department, where they detail their adventures in building and testing a valvular conduit. Long story short it works (kinda). The VC is more effective higher Reynold numbers. At the end of the page they show a graph of how the pressure drop across the diode varies with Reynold number. Anyone care to hazard a guess at the Reynold numbers associated with the flow in a pulsejet? My guesses came out very, very high (5 x 10 to the 6), which would make the VC ...potentially very effective? Comments?

Hi,

Here is a guy that apparently re-patented Tesla's conduit.

http://patft.uspto.gov/netacgi/nph-Pars ... PN/5265636

Al Belli

Narada wrote:it works (kinda). The VC is more effective higher Reynold numbers. At the end of the page they show a graph of how the pressure drop across the diode varies with Reynold number. Anyone care to hazard a guess at the Reynold numbers associated with the flow in a pulsejet? My guesses came out very, very high (5 x 10 to the 6), which would make the VC ...potentially very effective? Comments?

As far as I know, no one in the forum has built one. However, at least one pulsating combustor with the Tesla valve has been built to power the Tesla turbine by the people active in the Tesla turbine circle. I've never managed to make an assessment of those Tesla guys and their machines so it's hard for me to say how well it performed in comparison with other combustors. That same guy built quite a number of different combustors for that turbine but damn if I can understand which ones were good and which were crap.

The problem that I can see in the use of the Tesla valve for a pulsejet is that it's bound to be power-sapping. It adds volume to the chamber, lowering the confinement of hot gas. It uses some of the hot gas to turn it upon itself, which must consume some energy etc. I have no doubt that it works but it probably works like those wooly industrial pulse combustors -- a bit softly.

A long time ago, I proposed a cylindrical form of the Tesla valve, which you get if you rotate the original item around one of the long sides. You get a tube with a serrated central spike and a series of conical washers, which would be very easy to manufacture cheaply and just stack in a tube. It would also add another brake to the outgoing gas by making it alternatively expand and contract. I think just 2-3 stages would be enough for it to work quite effectively.

Biut, we should listen to our elders. Both Reynst and Foa claimed that no valve they had seen worked better in practice than just a straight tube of sufficient length to produce sonic choking.

To add to the above -- in my opinion, reasonable pulsejets use the forward flow for propulsion by turning it backwards, instead of fighting against it.

Hi guys
I just go to put my two cense in here. Having never made a valvular conduit what I'm saying is pure speculation so don't take it too litterally, but I have to agree with Bruno that it is probably power sapping. To start there are a lot of thearies on how it works but it is my beleif that Tesla's conduit simply uses up the energy of the exiting gas to stop the flow. It works by increasing the distance the gas travles as it exits compared to the distance it travles when it enters. If you trace the flow backwards you will see this. So what it does is add resistance to the gas by adding travle distance and uses up all of the energy in the form of friction. This is not at all like having actual valves that close that the gases can bounce off of, or like in a valvless pulse jet where the pipe is as short, and bent back so you can harness some of the energy the exhaust; However I am a big fan of Tesla and you need to look at it in the proper context. Perhaps the VC is the best fit for the disc turbine where there is going to be a load applied to the other end of the combuster it may have been needed to force the exhaust through the discs. It may be the only way it would work is with valves or the VC.

I made this and showed it to a few at the PJ meet.

I want to in the future try and make a valvless PJ, but I don't have access to a CNC machine anymore. Still trying to find a way around that though.

Good luck.

Well, I agree with you Bruno, it probably isn't the most efficient containment scheme. To be honest, I kinda had the same bone to pick with the lockwood. Seems to me that a fair amount of energy must be lost when the flow goes around that 180 degree bend. I wonder if there is a large enough body of experimental knowledge on the forum to compare how a lockwood compares to some of the more linear pulsejets, like the chinese or Larray's PWPJE. That is to say, different geometries, but the same combustion chamber volume. Cause I can say that I think the less changes in the direction of the flow that are made the more efficent the engine will be till the cows come home, but...doesn't mean much! Ah well, twas interesting.

Narada

Here's a faint imagine of a flow rectifier on a pulsejet.
Mark

Tidbit

Another thought.
Mark

A variation.
Mark

More from Paper 18.
Mark

A chart.
Mark

With jackets.
Mark

More
Mark