Has this jet/rocket concept got a name?

hi,

A pressure jet has venturis which use the energy in expanding propane to
entrain air into a combustion chamber.

a)
What about using the expanding propane (maybe ethane is better) to drive a
turbocompressor?

b)
And could this be used in a rocket too. An ethane tank held inside a warm
peroxide or nitric acid tank provides
expanding ethane which drives a turbine which pumps the oxidiser into a very
low pressure combustion chamber
The turbine exhausts ethane into the combustion chamber. The pressure would
have to be very low since
the ethane would be pumping a lot of oxidiser.


Could co2 be mixed with the ethane to increase the effectiveness of such a
system

Toby

A pressure jet has venturis which use the energy in expanding propane to
entrain air into a combustion chamber.

I did an experiment on this with a film-jet Transvector made by Vortec and also
available from Exair.

I used a Power Pal compressor as the pressure source, and suspended the
apparatus from a 3 foot brass tube hanging from the outlet fitting. It was a QD
fitting, and kept a seal while allowing rotation.

There was a water tank below the Transvector, and a paddle. By adjusting the
water level, various damping effects could be had.

There was a high pressure automotive tire gage at the junction between tube and
Transvector. A goose neck maintained a liquid drive to the gage, and an orifice
in the line was carefully adjusted by piercing with a pin to match the damping
of the water tank.

A tiny plotter pen on the tip of the gage traced out a plot on a bit of index
card. As the pressure was raised at various rates, a near straight line plot
was traced, repeating within three line widths on three traces.

My analysis was that the higher the pressure, the lower the amplification
ratio. The catalog literature for this device shows a constant amplification
ratio. My analysis indicated this was not an effective way of generating
thrust.

In the US patent literature, I found a lot of these ejector ramjet ideas,
often named "self-starting ramjet", which of course refers to the major
drawback of a ramjet, that it has 0 thrust at 0 speed.

What about using the expanding propane (maybe ethane is better) to drive a
turbocompressor?

I hope to try this. I have used a small bottle of propane to run any one of my
non-spark-producing air tools in places no air compressor can go. It's handy,
and a bit dangerous. The die grinder works well, but on metal work, it creates
sparks and can ignite the propane. So I figured, why not use propane pressure
to run up a turbine, and burn the vented fuel in the burner.

One good reason not to do it is that the overall fuel/air ratio is
non-burnable, requiring concentrated fuel metered into turbulent air to form a
flame that heats the rest of the air. It's hard to control flame behavior with
low pressure fuel. It is hard to deliver that fuel precisely, but there are
vapor-fuel burners on some engines, so it can be done. I refer here only to air
breathing engines.

Could co2 be mixed with the ethane to increase the effectiveness of such a
system

This was the same thing I ran up against when I looked at the problem. The
tendency is to assume that a tank of compressed gas provides constant pressure
as its contents are withdrawn. This is because vapor pressure is sometimes
quoted as a property of a substance. One eventually realizes that this property
is only at a specific temperature, and the heat flow required to maintain this
temperature while the contents are withdrawn is substantial.

After realizing that, you realize that what you're building there is a Rankine
cycle engine inside an engine. Lord Rakine invented the steam engine, a large,
inefficient heat engine. Still, regen cycle rockets exist and with careful
design, high heat regen ratios can be engineered.



Yours,

Doug Goncz, Replikon Research, Seven Corners, VA
Unequal distribution of apoptotic factors regulates
embryonic neuronal stem cell proliferation