ChrispenEvan said:

is this twaddle?

Don Baumea

In 1995, My research on subsonic ramjet engine design was sufficient to build a 55” long research engine.

According to the research, combustion processes create heat, which imparts energy to the compressed air, creating a dramatic expansion of the volume of air. That was the textbook explanation, snd still is. Therefore, to the degree that greater heat is created in the combustion process, the greater the thrust produced.

For decades I embraced this explanation of jet engine combustion physics.

Until I read in, “ Introduction to Airborne Radar”, that electromagnetic frequencies relate to various matter ( elements) in a range between fully opaque, to fully transparent. This is a fundamental fact.

As I understood combustion theory until recently, heat, which is primarily electromagnetic energy in the Infrared frequencies, excites kinetically the composition of atmospheric Air.

Now that it is clear that nitrogen, which constitutes about 78% of air, is transparent to Infrared energy, meaning no energy is transferred to nitrogen, it stands to wonder if There may be other EM frequencies, created in combustion processes that do impart energy to Nitrogen, but are not exactly known.

I have reason to believe that there may be a far more efficient way to expand nitrogen gas, without creating heat to achieve this. In other words, there may be a set of frequencies that create tremendous gas pressure without any heat, a cold gas system.

In my research ramjet, I evolved to burning metal powders as a way to create much more heat than liquid fuels. Then about 2012 I began exploring heat generated by electric arcs, which can be in excess of 30,000 degrees ( F).

Now in my new series of investigation with my research ramjet, I will be looking into using Em frequencies exclusively, in a range that imparts significant energy to Nitrogen, but without the detrimental infrared frequencies.

Nitrogen gas does not absorb infrared (IR) light because it is a symmetric, homonuclear diatomic molecule with no dipole moment. For a molecule to absorb IR, its bonds must flex, creating a change in dipole moment, which symmetric nitrogen cannot do. Therefore, infrared radiation passes through nitrogen without causing it to heat up, making it transparent to IR.

There is significant data on the interteraction of nitrogen to EUV, Extreme Ultra Violet frequencies.

A unique EUV lazer would be the best candidate to inject high energy EUV into the what was formerly the combustion chamber, but now would function as only an nitrogen expansion chamber, a dramatically different component.

The significance of this single modification , to the ramjet cycle, is not readily apparent, it would create the dynamic internal flow to operate without any fuel, fuel injector, and flame holder , and in theory, allows operation from subsonic thru and into the hypersonic range.

I’m not sure, but it kinda boils down to how much power would be needed by that EUV laser to heat the nitrogen/air enough to get useful thrust relative to the battery/power unit needed to generate that much power. And it would be very substantial I imagine and so quit heavy.
FWIW a 747 engine combustor section generates the equivalent of about 100,000 hp and in a small volume. The majority of the energy in the air that exits the combustors is converted by the turbine section from heat/speed to rotational torque that makes the engine spin. Each stage of the turbine extracts energy from the very hot gas (it enters the first stage of the turbine at a temperature of about 300° hotter than the melting point of the metal in the turbine blades and stators, hence it’s beyond critical that they get cooling air all the time) and so by the time it exists the engine it’s much cooler. Though still rather toasty.

Anyway I find it difficult to see how a subsonic ramjet will be efficient. They usually only start to get efficient (a relative term as they aren’t very efficient overall especially when compared to jet engines, and are only really used when speed higher than a jet engine can sustain is needed) when above about Mach 2 or so from memory. Changing the heat source is, I suspect, not really going to change that dynamic.