Melenric Pressure gain jet patent 3188804

[racketmotorman]

Hi Bruno

LOL... I'll drink to that :-))

Cheers
John

[Bruno Ogorelec]

Hi Bruno

LOL... I'll drink to that :-))

Cheers
John

A drink is always in order, I say. I'll have a dark Goesser beer. Very good!

I want to clarify and amplify what meant when I wrote

Yes, we may end up using radial turbine and compressor wheels and heavier construction. Yet, we may shed so much weight from the compressor stage that this may not matter.

A normal turbojet must have high pressure at combustor inlet. That is, it must have compressor. A pulsejet doesn't. Nothing -- no weight or complexity -- is necessary merely to make the thing work.

Unlike a conventional turbojet, this thing start with zero complexity and zero weight of the compressor and turbine stages -- yet it works. Nice, huh? Not a bad advantage over the 'normal' turbojet, which must be a fairly complex and expensive machine to work at all, no matter how poorly.

So, add a pitiful little turbine and a penny-ante compressor and the thing not just works, but (hopefully) works rather better. So, we boost it until we get to the same level of performance as some benchmark conventional turbojet. Then we stop and look at our contraption.

My expectation is that it will be vastly cheaper than the conventional competitor and probably lighter. Could be somewhat bulkier, though.

But, let's look also at the ancillaries. No starter necessary. You start one combustor by farting into it, it fires on its own, slowly spools up the wheels and you let the other combustors ignite. Neat, huh? A damned sight easier than a conventional turbojet. How much weight, complexity and money have we spared?

OK, I won't bore you further. this is just food for thought, anyway.

[Viv]

Hi Bruno and John

Interesting comments on all sides and with valuable points and insights, thats how this place is supposed to work;-)

I like Bruno's summary of the topic so far as we all have our place in what he is saying and the I think the best point is simply the list of what we have.

An engine that runs with out any moving parts that can be improved by the addition of only a few more simple parts.

The trick as always is for the sum of the parts to exceed the individual parts.

Now if I can get timed ignition in to this I will be a happy man;-)

Viv

[Viv]

John

I should take note of what you said about the direction people are approaching this subject from, as you say you are a turbo guy and we are Pulse guys.

Its worth noting that the interest Bruno I share and engine projects we have collaborated on do not have pulsating exhausts as a design goal, pulsating combustion is one thing we are interested in yes, but pulsating propulsion is not some thing we are prepared to accept as given.

Your comments about pulses and turbines are noted but Bruno and I both know we can get rid of the pulses to solve your other problems with construction strength and how heavy the components end up.

Viv

[racketmotorman]

Hi Guys

When Rolls Royce were given the contract to build their first jet engines , which at that time were very simple units compared to the extremely complex V12 aeroengines they were making , RR are reported to have said "We'll soon fix that", and the complexity grew from then on , but so did better fuel efficiency , thrust , reliability etc etc .....
And probably most important from an aero engine point of view , frontal area per pound of thrust produced , a bulky aero engine is useless .

A modern 50,000 lb thrust engine has a frontal area only the size of its compressor wheel, anything larger create too much drag , and drag is a "killer" for aircraft . Those 50,000 lbs of thrust come with ~60 sq feet of frontal area , thats better than 800 lbs of thrust/sq foot

From what you've said so far it appears as though you interest is making a gas turbine using pulse combustion , something already being worked on by the "big boys" of the aero industry , for a considerable time I'm led to believe , still without success :-((

Even though the "exhaust" might not be pulsing , the pulsing required for "compression" is still going to be a problem other than in small units.

Tell me more :-))

Cheers
John

[Ash Powers]

Take this simply as my 2-cents worth, but when I look at an engine design, there are a few parameters I take into account....

The fewer number of components within the engine is an advantage.

The fewer number of gas-state variations, the better.

The greater the conversion of potential energy stored within the fuel into usable work, the better.

The greater the energy density produced by said engine, the better.

The design of the engine this post is based on, to me, is really nothing more than a creative assimilation of a gas turbine and a pulsejet engine. Although the creativity involved in meshing the two technologies is commendable, I strongly doubt the increase in complexity will produce any significant improvement in the other factors I stated above; namely efficiency.

Qualitatively speaking, the additional materials and gas state variation required in this construct are going to produce thermodynamic losses greater than found within a pure turbojet design. In addition, because the combustion process occurs intermittently within the chambers, the large swing of temperatures in the gases will introduce further inefficiencies. What I have stated thus far is just scratching the surface in terms of the additional losses involved with such a design, but illustrates the fact that at least two of the most prominent factors involved in determining efficiency will be compromised by the "complication" of this design...

[Viv]

Hi Ash

Yes your right and no ones arguing:-) mainly because we have moved off topic a fair bit since we started, not unusual for the forum but thats the fun of it.

The most notable thing about this particular configuration was the fact that the power turbine was driven from the intake pulses not the more powerful exhaust pulses (pulses and turbines were discussed by John).

From there it gets worse as you point out, but pressure gain is worth having if it can be added with out detracting from the pulse jet or the turbine.

Its the maths thats the problem with it subtracting one from another rather than adding up to some thing greater than the individual parts.

Melenric is interesting as SNECMA is interesting, and you will note Bruno's comments on their layout.

For myself my money is on trapped vortex combustion and a counter intuitive programming of the stability programs drive algorithm.

Viv

[Bruno Ogorelec]

The Melenric should not be looked at as a turbojet with pulsating combustors. It is most definitely not. Instead, it is a turbocharged pulsejet. The difference may sound semantic, but it is not.

Look at the layout and imagine the pulsejet combustors inside as cylinders in a piston engine. Pulsejet intakes play the role of piston engine exhaust ports.

Exhaust flow from the 'intakes' is used to drive a turbine, which drives a compressor and ups the inlet air pressre for the 'cylinders'. Just like on a turbocharged piston engine.

The main exhaust flow is left to perform its usual work, just as the major part of the energy of the expanding combusted gas is used to drive pistons and turn the crankshaft.

Looking at it as a turbojet is misleading.

It is not a pulsating turbojet, just a boosted pulsejet. It remains cheap and simple, compared to turbojets.

If it also captures waste heat from the pulsejet part and uses it to expand and accelerate additional air in a Meredith-style duct, so much the better.

[Viv]

For those not familiar with Dr Meredith and the importance of his work, here are a few background links

http://www.hq.nasa.gov/office/pao/Histo ... /ch5-5.htm

Heres another interesting link

http://www.supercoolprops.com/articles/ ... ooling.php

Viv

[Irvine.J]

Thanks for that viv, that Mr Meredith was a real pioneer and paved his own roads, its quite inspirational really, I can see some of the dissappointments he would have suffered to follow his gut instinct.
Thanks for post it was a good read.

[Bruno Ogorelec]

Thanks, Viv. Good links. Hope they make people think. It's an interesting issue, given the huge amount of waste heat in pulsejets.

[LINZ]

Viv
What did you say??

"For myself my money is on trapped vortex combustion and a counter intuitive programming of the stability programs drive algorithm."

Who's using a stability program for trapped vortex combustion and what intuitive part of it would be improved by doing it counter intuitively???
Confused but intrigued LINZ