Prerequisites by Topic:
Hydrostatics. (5 classes)
Control volumes & momentum. (4 classes)
Energy, Bernoulli equation. (3 classes)
Dimensional analysis. (3 classes)
Pipe flow. (4 classes)
Boundary layer, lift and drag. (5 classes)
Compressible flow. (7 classes)
Fluid meters. (4 classes)
Navier Stokes equations. (2 classes)
First and second laws of thermodynamics, momentum and continuity relationships
Mass balances
Specific volume evaluation for multiphase, ideal-gas and incompressible substances
Energy balances
Internal energy and enthalpy evaluation for multiphase, ideal-gas and incompressible substances
Availability concepts
Availability balances
Entropy evaluation for multiphase, ideal-gas and incompressible substances
Mixtures of ideal gases and water vapor
Reacting mixtures
Compressible flow; Gas Tables review
Cycle analysis
Constant area flow, normal and oblique shocks, Prandtl-Meyer flow
Compressible flow
Inlets, diffuser and exhaust nozzles
Compressors
Burners
Turbines
Component matching and system operation
There must be a more fun way to figure out jets? Frank Whittle didn't have all these prerequisite classes, knowledge and understanding, at least not formally, did he? I think he just jumped in and learned by doing... that's for me. Heck, this is my life, my brain, my time, my money, my blood (skinned knuckels) and I am a "free" American living in the USA (land of the free?) which ought to be all the prerequisites I need, right? So I decided I can learn it any way I want! I tell you, I cannot get interested in a Brayton cycle or enthalpy evaluation unless I really really think I want to know and need to know what the heck they are. And when you don't know anything, you don't know you need to know that stuff.
I think they should teach the stuff backwards. Give me the cool, fun, interesting, "turn-on" stuff first then let me ask, wonder, and explore the dry details later when I may know why maybe enthalpy fits in to the cool thing I want to understand. Land me at the top of the mountain then teach me how it is held up. (if you know).
If Frank could do it so could I! Could I?
I figured that some old guy (probably dead by now) figured out
how to make the first turbine jet engine a long time ago, so
why can't I? And, heck, this guy (Frank Whittle) didn't know
that it would really work, and he didn't see a cut-away of a
working model in a museum when he was 10, like I did, so I
have a giant head start over old Frank.
Cheat Larry, if you want to do it in this life time!
I started with a used turbo charger from an old car. It cost
me only $20.00 because the guy who sold it to me thought the
bearings were shot, I did too (An example of how ignorance can
work to your advantage). Frank (builder of the first
turbo-engine) didn't have a turbo charger with hydrodynamic
bearings, computer designed and balanced compressor and
exotic-metal hot-side cast wheels to start his project with.
Man, I thought, with all this cool stuff in hand, this should
be a piece of cake!
Am I nuts? I truly thought I must be the only stupid idiot on earth, crazy enough to try and make a jet engine with a turbo-charger from a car. At the same time I "knew" it would work. I just thought it was dumb because it would have no chance of working good enough to have any purpose. To a person, everyone who I told would say to me: "why", "what can you do with it?", and I never found a short answer that anyone understood (or a long one for that matter). Years later I learned that there were many that had gone before me. My project was not stupid. Wow, so someone has already invented a wheel? I didn't know it was possible to, not only make a jet engine based on a car turbo charger, but that it actually works real good. It works so good that it was proposed (in secret of course which probably is the reason it failed) as a low-cost engine to power cruse missiles during the Vietnam war. Heck, for a cruse missile, the engine only needed to work one time during its short flight because if things work right everything gets blown up! I think another reason it wasn't developed could be that it wasn't expensive enough for the government, and no self respecting cruse missile jet engine designer would ever "design-in" parts that can be found at your local auto-parts store.
Thinking I was a pioneer I pressed on. If I knew that this had been done time and again for over 20 years, I would not have continued, I think. My first goal was to make an engine that would run without any outside assistance other than fuel and oil being pumped in. With the turbo-charger, some scrap steel pipe, propane gas, an oil pump, and a shop-vac to start it, I made my first jet engine in one week. I thought all I had to do was connect the output of the compressor to the input of the "hot-wheel" (which drives the compressor), add fuel somewhere and let it "explode". I thought the explosion would "flow" out the back because all this air was flowing in the front pushing it out the back. In a way this touches on an important concept in the function of the jet engine, but I didn't understand it at the time. I used the "exhaust" of the shop-vac (vacuum cleaner) to spin the turbine by forcing air into the inlet. I turned on the gas and lit it off with a propane torch at the jet-engine exhaust pipe. It took days to get it burn and remaining burning. I had to shield the flame so the high speed air coming in wouldn't blow it out. I thought it was a air/fuel mixing problem. I began to realize that it was not an "explosion" that makes this thing go. It is not like a internal combustion engine at all. Yes there is compression, combustion and expansion, but not in well defined steps like a car engine. It all happens all the time, continuously! That is way different. There are no cycles, strokes, valves, cams or pistons, just one rotating shaft with 2 or more fans on it. The "combustion" is more like a burn, like a blow torch, like a flame and lots of air going buy it. You have to ask what keeps the flame from literally blowing out by all this fast moving air? That is the trick I didn't understand or appreciate in my first design and the cause of my failure.
Failure is my teacher. It just would not run.
If it didn't work at all I may have just given up, but
instead it worked just enough to get me hooked. Actually
it ran all by itself for over a minute one time only and
would not run again no way, no how, no matter what I did.
Like my uncle Al's big fish story, it got away. I tried
for weeks with total failure. The more I tried the more
hooked I got, going down a path seeking knowledge into a
bottomless pool of personal ignorance which I found to
grow larger, not smaller, with every new thing I learned.
I knew I had to make the "combustion" chamber (HB) much larger. If it was large, there would be room for the fast moving air to slow down and give it more time to heat up and expand and make room so the flame blast is not directly on the hot wheel.
So thats it, scrap GT#1, buy another turbo-charger from a wrecking yard for $25 and start designing GT#2 .... Back to the main jet page: Larry's gas turbine jet engine
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