M1E Preview

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Mike Everman
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Re: M1E Preview

Post by Mike Everman » Fri Oct 08, 2004 3:48 pm

Just a quick note, on my way out for three days of fishing, drinking and telling lies...

Could it be that the UFLOW mach numbers were "what is the speed of sound in this region?" not "how fast is the gas going?" certainly the velocity column must be telling us the gas speed with respect to the observer outside, but it may not be exceeding the internal speed of sound. I don't have time to look, but comparing the velocity column to the Mach number column will either show parity or not.
Mike
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jmhdx
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Re: M1E Preview

Post by jmhdx » Mon Oct 11, 2004 7:06 pm

Does anybody know the speeds of sound at say 500,1000,1500 degrees centigrade?
I had thought that the pheonix b.c.v.p engine failed to run for more than a few seconds(or was it less) because the mean tube temperarture had increased making the tube effectively too short when hot.
Not so critical in other engines.
If the difference is small then I thought wrong.
Mike.

Al Belli
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Re: M1E Preview

Post by Al Belli » Mon Oct 11, 2004 8:01 pm

Hi jmhdx,

For an online calculator, go to http://hyperphysics.phy-astr.gsu.edu/hb ... ouspe.html

Al Belli

Graham C. Williams
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Re: M1E Preview

Post by Graham C. Williams » Mon Oct 11, 2004 10:57 pm

'I had thought that the pheonix b.c.v.p engine failed to run for more than a few seconds(or was it less) because the mean tube temperarture had increased making the tube effectively too short when hot.'

The temperature gradient does change across the motor. This tends to alter the frequency of operation. The wave form across the motor is reasonably stable over the gradient. Yes, it tends to favour one curve. The big problem is breathing.

Graham.

jmhdx
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Re: M1E Preview

Post by jmhdx » Tue Oct 12, 2004 7:22 pm

Al Belli wrote:Hi jmhdx,

For an online calculator, go to http://hyperphysics.phy-astr.gsu.edu/hb ... ouspe.html

Al Belli
Thanks Al!. The difference is large indeed although I appreciate its not a straightforward application of the math to calculate the effect on pulse combustion.
I think we can conclude though, that faced with cold air at one end and hot co2 at the other the expanding gases will favour exit from the rear of the chamber. Ofcourse its a typically over-simplified thesis.
I'm thinking that a well tuned engine will be a b*stard to start cold.
Perhaps thats why mine won't run!
Mike.

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