Real VPJ stats
Posted: Fri May 22, 2009 4:58 am
Hi all,
I'm not a builder, but dable in the theory.
As such, Uflow1d has been invaluable,
I am getting to the stage where I think I can ask it meaningful quastions and get vaguely meaningful results.
What I would like, is the dimesions of a real pulsejet someone has buld, and its resonant frequency.
Something "linear" like a lockwood would be best.
Could someone provide these please?
The reason:
Bruno (where is he) and I used to debate kadency vs. acoustic resonance.
I can now see the two separate effects in uflow1d, and they seem to have considerably different timescales.
Thus, If I put a real vpj into the simulation, and know its resonant frequency, I should be ale to tell what is really happening.
I have done this with some guesswork,
e.g. a 1 meter long lockwood resonates at about 200 hz, etc.
However, the model seems to indicate that this is way off for kadency, assuming a "full" combustion chamber each time.
The implication is that in reality we get limited recharge of the chamber, and.or limited mixing.
I think that I can work back from real data to provide a figure of % effectiveness of the engine,
where a full recharge of the CC would be 100%.
My guess is that current engines don't breathe well, and the same power (or just fuel consumption, more likely)
could be generated by physically smaller engines if we could improve this proposed cyclic CC recharege efficiency.
Its all a longshot, and highly specularive for now, but a real set of statistics (or several for different sizes/designs)
would be a good starting place.
Pretty please?
Don
I'm not a builder, but dable in the theory.
As such, Uflow1d has been invaluable,
I am getting to the stage where I think I can ask it meaningful quastions and get vaguely meaningful results.
What I would like, is the dimesions of a real pulsejet someone has buld, and its resonant frequency.
Something "linear" like a lockwood would be best.
Could someone provide these please?
The reason:
Bruno (where is he) and I used to debate kadency vs. acoustic resonance.
I can now see the two separate effects in uflow1d, and they seem to have considerably different timescales.
Thus, If I put a real vpj into the simulation, and know its resonant frequency, I should be ale to tell what is really happening.
I have done this with some guesswork,
e.g. a 1 meter long lockwood resonates at about 200 hz, etc.
However, the model seems to indicate that this is way off for kadency, assuming a "full" combustion chamber each time.
The implication is that in reality we get limited recharge of the chamber, and.or limited mixing.
I think that I can work back from real data to provide a figure of % effectiveness of the engine,
where a full recharge of the CC would be 100%.
My guess is that current engines don't breathe well, and the same power (or just fuel consumption, more likely)
could be generated by physically smaller engines if we could improve this proposed cyclic CC recharege efficiency.
Its all a longshot, and highly specularive for now, but a real set of statistics (or several for different sizes/designs)
would be a good starting place.
Pretty please?
Don