FWE Theory - Focused Wave or NOT Focused Wave?

[Mike Everman]

Let me know if you want a recommendation letter to MIT. I am friends with the former head of Aero-Astro dept, and an ME department professor. I don't know how much "pull" I've got, but I know these guys respect my opinion, and I think you'd be an asset to them. Expensive school, though...

[Eric]

Wow Mike, thanks for the offer. I would love to be able to go to MIT, if only I got some super duper financial aid to cover the ( close to 40,000 a year i think?) tuition.

I finished a really high res composition of 30 different data lines and over 2580 hand entered data points. If I can figure a way to render it nicely I will post a pic. As it is right now, If I try to make a mesh out of it, my computer locks up.

Eric

[Al Belli]

Hi,
A friend related this song to Me ( sung to the tune of The Mickey Mouse show jingle ) :
MIT, PHD , money.

Al Belli

[pezman]

I think that PSU's aero department is pretty well regarded (ranked 10th best undergrad school for aerospace engineering), so it should at least be a decent springboard for getting into grad school -- and folks seldom pay tuition while going to grad school. They take it out of your hide.

If you want to visualize flow in a pulse-jet, ditch UFLOW and get involved with the Gas Dynamics group in the ME department. Might even make an interesting research topic to compare the actual flow in a PJ to predictions based on the 1-D Euler solutions.

If you get involved w/ a research department and do good work, you can generally get a recommendation that will give you a substantial edge.

[Mike Everman]

Too true, all. I wish the proper code weren't so expensive! We'll have to muddle along, taking the "results" with a grain of salt. Those of you who are university students have access to some remarkable tools that most of us can only dream about in the way of code and computing muscle, if you only dig around a bit.

[mk]

Very interesting stuff! (I spend over an hour to resd the posts of the last two a half days.)

(1)
To the "1/4 or 1/2 induction pipe wave oscillator":
Larry, why do you want the the intake rather to be a 1/4 wave oscillator? Putting an internal ("Rosco-style") intake (induction pipe) to an FWE/ Thermojet/ Chinese type engine pointing (eventually rightangle) against a/the_front wall and only leaving a small gap would, at least IMHO, lead you to disadvantages caused through flow effects.
Why not staying to the point of optimzation of the 1/2 wave oscillator induction pipe for avoiding flow caused disadvanteges?

(2)
To the fixed pressure antinode discussion:
IMHO the pressure antinode is more a "fixed" region from the front wall to the inner outlet of the induction pipe - short: just as Graham mentioned. But this needn't to be a problem, considering a neglible(?-from "neglect") x-axis tolerance of oscillation issues up to +-2,5°/+-0,0437(arc) for an antinode region. The front_wall-L/8 region would actually fit this tolerance.

(3)
To the augmenter assimilation distance discussion:
Look at the video. As you can see the shut-off point of the engine is reached at a relatively long distance between the intake/induction pipe mouth and the cone (which is used as an augmenter) mouth. Also notice the engines changes in sound.
-- file follows tomorrow, I don't have it on this PC, sorry --

[larry cottrill]

(1) To the "1/4 or 1/2 induction pipe wave oscillator":
Larry, why do you want the the intake rather to be a 1/4 wave oscillator? Putting an internal ("Rosco-style") intake (induction pipe) to an FWE/ Thermojet/ Chinese type engine pointing (eventually rightangle) against a/the_front wall and only leaving a small gap would, at least IMHO, lead you to disadvantages caused through flow effects.
Why not staying to the point of optimzation of the 1/2 wave oscillator induction pipe for avoiding flow caused disadvanteges?

Marten, it was just something to try. I think the original problem was that Ross could get his engine to run with the deep intake, once it was located rightly, but it seemed to burn pretty far back in the tube, so I suggested putting a cap on the end to disperse the air/fuel mix sideways. This causes a wave reflection which makes the intake a 1/4 wave pipe - but what's so wrong with that? You're using the pressure antinode to spout the air in with pressure rather than velocity, and the intake pipe can be shortened. The reflective plate would only need to be about half a diameter from the end of the tube for it to not greatly impede the flow. Of course, I have no idea whether that will even work ... it was just something to try, since Ross was in an experimenting mood ;-)

The other way to do this, then, is to bring the intake in from the rear. Then it occured to me, Why wouldn't the best spot in that case be right up against the highest pressure swings in the whole pipe, with the intake again acting as a shortened, 1/4 wave element?

Probably ridiculous and impossible to get working, or somebody would have discovered it already.

L Cottrill

[Eric]

WARNING: VERY LONG ANTI-PSU RANT BELOW

PSU looks fairly good on paper, but unless you start directly at main campus it is far from a fun experience. The campus I started at, hardly any of the teachers spoke English as a first language, and most of the people were brought over from other countries and didn’t even know the basic words to describe the things they were teaching.

Our calc teacher for example kept on saying "Deruotue" in a really heavy russian accent, it took us all 2 weeks to figure out "Deruotue" meant Derivative between his wild gesturing and all.

Physics was also quite "fun", our physics professor was ranked #3 physics teacher in China, which was great except he didn’t speak english. He knew a little bit of english, about as much as you could learn from a translation dictionary on the plane flight here. He would draw little pictures on the board and point at things and make motions and make noises like "bang" "pow" to show a collision. When someone asked a question he would go "ya ya ya" and start mumbling in chinese, and would generally use ya ya ya when he got stuck trying to show something. The one class he went ya ya ya 245 times. It was really pathetic, luckily I had 2 years of honors physics in high school taught by a very excellent teacher. After getting 100's on the first two tests, and being asked to be a tutor for $$, I stopped attending class ( with the rest of the class) and I still ended up with an A.

The honors program was a total joke, and independent study research rarely consisted of more than writing a 2 page paper and making a poster. Of course the one half way competent teacher I had for an advisor wanted me to build a 3 dimensional resin model printer out of a computer printer and a Pentium 2, but he essentially wanted to take credit for it :(.

Not only was it a joke but when I applied they said I would get all these special privileges and get first pick at classes and the best dorms. Of course I got totally screwed over, and was one of the last people to have my schedule entered, didn’t get any of the classes I wanted. And of course I got stuck in the crappy dorms when other people who didn’t even apply for the good dorms got in. When I went to pick classes they handed me a sheet of freshmen classes and then proceeded to X out all the classes that were full, so out of a sheet front and back of classes I got to pick from about 10, including ball room dancing, literature for women, and many other things that had nothing to do with my major and that I absolutely would go insane having to go through.

Another thing that made me very angry was the faculty and their total lack of interest in anything. The engineering department didn’t want the kids to do any special research type projects. I was actually able to start an engineering club and get a lot of members ( I later learned the same engineering department basically struck down any engineering type club as it was being formed so they wouldn’t have to do any extra work). So we have all these members who attend the meetings and we apply for funding (the campus gets $80,000 to distribute to clubs each year, and if its not all used it gets sent back to main campus). Well we put together a proposal to get funding to get equipment. (oh yea I forgot to mention the 9 CNC lathes and milling machines that were just sitting in storage that none of the teachers wanted to get set up, and the plasma cuter, the sheet metal roller, the hydraulic pipe bender, etc etc....). So We apply for 10,000 funding ( not a lot for a club of 60+ members when you consider the exercise club got 12,000 for new treadmills and they only have maybe a dozen members), they fought and fought everything we tried to do. First they said that there was no place to do this stuff, so we pushed and said how about in the big building the other stuff is being stored in? They then tried to say that the students didn’t know how to use the equipment, A teacher stepped forward and offered to teach classes. They then said that it was unsafe and too much of a liability, we mentioned their incompetence and how they have been basically sitting on their asses collecting salary for the past 20 years and then they decided to give us 2500 after we made a bit do to about it all. So now we have a perfectly good brand new still sealed in the box Lincoln Electric Precision Tig 185 Tig welder, that they absolutely positively refuse to install a 230 v 50 amp line for ( welder was purchased over the summer by one of the engineering teachers without our knowledge, and quite a good choice since it cant be used).

Even at main campus the teaching situation isn’t great because you have class sizes up to 300 for major classes, and as far as the in depth aerospace classes the teachers are apparently not very great. Each year 100 students are accepted into the aerospace major, and each year only about 10 people graduate, the one year it was like 6, and we are talking about 100 of the smartest kids out of 80,000 students.

That’s all just the tip of the iceberg, and don’t even get me started on the below 3rd world developing country prison quality cafeteria food...... now for something that can make this post seem somewhat on topic.

Well I was hoping to make a nice graphical display using mesh but when I try to make a mesh out of certain segments autocad really botches the meshing up. I will probably just compile all the lines and show them like the other graph. It does a really nice job of showing wave reflections in 3d form which are much easier to see when you can spin the model around.

I think I am actually going to build a F.W.E out of Pyrex and use cooled oil, which will have the same refractive index. Then just have the engine run for half a second at a time and have high speed camera record it. Maybe inject a bit of smoke or highly reflective powder and see things in very slow-mo. I actually made a F.W.E. out of very compacted snow today. It kind of resonated for about 1/4 a second, not like it was fully running but it was making muffled noise. I used the same technique to blow up a hollow snow man.

Eric

[Mike Everman]

Bummer. Eye opener. Sorry.

On the 3d plot, I wonder if you can just put the bitmaps on different elevations, and not use mesh at all? I think I can do it with Sworks, I'll check..

[steve]

perhaps the college discussion should be moved to off topic but...

have you looked at Embry riddle or Flordia tech? I believe riddle is ranked #1 in areospace engineering. Flordia tech also has an excellant engineering department- I almost crapped my pants when I saw the machine shop and wind tunnel. A student that I talked to there was very happy with the program and was even getting paid to conduct research with one of the professors. I also spoke with one of the professors for over an hour about various types of jet and rocket engines while my parents just sat there wondering what the hell we were saying. I havent talked to professors or students at embry riddle yet, but I have toured the school twice and what I saw was very impressive. I will be visiting it again in a few months, because I still haven't decided which school I will be attending. I was leaning towards ER but then FIT just offered me a $40,000 scholarship so I am still unsure.
needless to say, I am looking foward to college.

PS. the food at both schools was pretty good

[Al Belli]

Hi Eric,
I was an instructor in industry for a PSU administered, Ben Franklin grant funded, five year Cellular Manufacturing course that was a full time position for Me. I developed the curriculum, and taught the various modules to 167 students at the company's facility. Cooperation from the campus administration was almost non-existant, and most of the credit for the functioning of the program was given to the " Instructor of Credit " who I saw four times during the five years that I taught this program !!! Fortunately for Me, the company appreciated My efforts, and arranged for Me to perform some non-PSU instruction with a generous bonus to compensate for the paltry wages paid by PSU. The program grossed over $1,200,000 with PSU retaining the customary 51% off the top which went into their " general fund ", as is customary with PSU's general accounting practise. Had it not been for the company's in - kind funding, the program would have been a disaster.
You are entirely correct in Your observation that the satellite campuses are nothing more than a junior - college level institutions, however the main campus is excellent in many respects. I could have sent My two sons to PSU at a greatly reduced tuition, however I instead had them attend Ithaca college, Ithaca NY , at an annual tuition of over $27.000 each. They both graduated with degrees in computer science, and received generous scholorships from IC. If You can't transfer to PSU main campus, I would highly suggest finding another institution to attend. Don't be discouraged by Your experiences at PSU, there are many excellent colleges and universities from which to choose. Stay positive in Your quest for an education, and You will reap Your just rewards.

Al Belli

[Graham C. Williams]

Hi Eric,
Stay positive in Your quest for an education, and You will reap Your just rewards.

Al Belli

Dear Eric.
It's the best present you could have. Have you looked at other countries? Perhaps Oz or Imperial Collage London, it might be worth a try.

Graham

[mk]

(3)
To the augmenter assimilation distance discussion:
Look at the video. As you can see the shut-off point of the engine is reached at a relatively long distance between the intake/induction pipe mouth and the cone (which is used as an augmenter) mouth. Also notice the engines changes in sound.

OK, here's the video in WMV format.

Man, $27,000 or even $40,000 a year for studying! Who the hell can pay so much money without a scholarship??
I really understand the U.S. American parents saving money their whole live from the point their child was born...

[larry cottrill]

Just to keep the thread off topic for a little while longer ...

I had never heard of Embry-Riddle until Steve mentioned it earlier on. But lo and behold, on the way home yesterday or the day before, the local NPR station was talking about Delta Airline's re-vamping of their fare structure at the low end, and there they were, interviewing an expert who was a professor of aviation transport economics or some such from E-R! Sounded like the guy knew his stuff, too, not like he was just talking off the cuff. What I thought was interesting about this is that from what Steve said, it sounded like a kind of high-level "technical school", whereas they obviously do teaching and research on the business aspects of aerospace as well. That two or three minute interview made a very favorable impression of the school, in my opinion.

If this seems like an odd thing to bring up, consider that even in engineering, one of the practitioner's main requirements is to provide solutions that are economically feasible, as well as meet functional and safety requirements, etc. The economics of engineering is basically the reason we don't have tornado-proof houses, crash-proof parking ramps, etc., not because the technology doesn't exist to design and build them.

L Cottrill

[jmhdx]

(3)
To the augmenter assimilation distance discussion:
Look at the video. As you can see the shut-off point of the engine is reached at a relatively long distance between the intake/induction pipe mouth and the cone (which is used as an augmenter) mouth. Also notice the engines changes in sound.

OK, here's the video in WMV format.

Man, $27,000 or even $40,000 a year for studying! Who the hell can pay so much money without a scholarship??
I really understand the U.S. American parents saving money their whole live from the point their child was born...

Great clip Marten. You've got a lot of things right there, sweet running and good heating just like the lockwood pics. It's geometry is sound and you built it with minimal tools and materials, thats impressive. Your cumbersome looking fuel injector is actually rather good, could you describe it again?
Mike.