Jet Engines 101

[Sandman]

http://www.geae.com/education/engines101/

[gofaster]

What's the difference between Axial Flow and Centrifugal Flow?

[cpxxx]

Ok I spent fourteen years in jet engines, (painful) let's see if I can remember this.
Axial flow engines have a series of disks with blades mounted on the rim. Like the fan seen at the front of every airliner's engine. Each disk and blade set (stage), sometimes fifteen or more, gets progressely smaller as each stage compresses and heats the air until is burned in the combustion area and  used to turn a number of turbine stages which then turn the compressor stages.  Essentially the airflow is straight through the engine.

The centrifugal fan is shaped like the familiar supercharger or turbocharger. The air is fed to an impeller rotating at high speed which flings the air outwards centrifugally through ducting and fed to the combusion chamber which in turn drives a turbine which turns the impeller.  Usually there was only one stage although there were one or two engines with a second impeller

http://www.gasturbine.pwp.blueyonder.co.uk/Nene1.jpg

http://www.gasturbine.pwp.blueyonder.co.uk/Derwentcut.jpg

The axial flow engines allows for greater compression and thus greater power and where a lot slimmer aerodynamically.  The Me262's Jumo engines were in fact early axial flow engines if rather crude. The early British engines were mostly centrifugal flow.

All modern turbine engines are axial flow.

[Scootter]

http://www.midlandairmuseum.org.uk/thejet.html


AND

http://www.midlandairmuseum.org.uk/thejet.html

[LePaul]

In flight school, I recall "suck, bang, blow"

I'll let our regulars pick that apart accordingly  

[devious]

Great link - my son had fun !

[Sabre]

Originally posted by LePaul
In flight school, I recall "suck, bang, blow"

I'll let our regulars pick that apart accordingly  

LOL.  When I was doing ground school for my private pilot's license, we were going over the four cycles of the horizontally opposed internal combustion engine.  To help us remember, the instructor labled them as follows: Suck, squeeze, pop, phooey!  Couldn't stop laughing for the rest of the day.

[Heater]

Originally posted by Sandman_SBM
http://www.geae.com/education/engines101/

Only problem with this site, is it's GE, Pratt makes real engines

[Sandman]

I dunno about other aircraft, but the GE engines on the F-14D far exceed the performance of P&W engines.

[SLO]

Originally posted by Sandman_SBM
I dunno about other aircraft, but the GE engines on the F-14D far exceed the performance of P&W engines.

try the SR71 BlackBird(PW eng)......it FAR out performs any F14's:D

[cpxxx]

Aah Pratt & Whitney 'Dependable Engines'
P&W's TF30 in the F14 had a surge problem which led to flame outs. That could ruin your whole day during a Cat shot.  

The SR-71's engines were very special with a special fuel too.

But P&W are for the most part good engines. I hated their manuals though, huge things with cheap nasty binders.

Speaking of paperwork. I remember when we got a contract from USAF to convert some civilian engines to military spec, JT3D to TF33 for the KC135 tankers.  We got tons of manuals we didn't need from the Air Force. All sorts, Technical Orders, Mil Specs covering everything from shop safety, to paint and even a fascinating manual which translated Top Secret and Classified into every language in the world among other things.  I learned all sorts. (I now know the truth about Roswell) But I wondered if the USAF knew they were going to a civilian organisation in a non Nato country. Anyway I locked them in a cupboard and marked it Top Secret (in English) just in case some Soviet spies happened by.

[Smut]

Originally posted by Sandman_SBM
I dunno about other aircraft, but the GE engines on the F-14D far exceed the performance of P&W engines.

Not exactly. Granted I'm an avionics dude for the most part but I've worked some engine programs in the past (F404-GE-402 EPE), and I was a Tomcat maintainer (A/B/D) in the fleet.

It is my understanding that the P&W TF-30 is actually a better engine (more power) high and fast (above mach) than the GE F110.

Late model TF-30's are also pretty reliable. The GE F110's have had their own share of reliability issues (which has sadly led to aircraft / aircrew lost). A/B burnthrough, anyone?

The F404 series (another GE product) in the F/A-18A/B/C/D has had it's share of "issues" as well. Somewhere around here I have pictures of one that exploded on the takeoff roll. Most impressive fireball. Pilot got out ok, aircraft was lost. One of the System Safety bubbas down the hall from me has a little blob of metal from that mishap...it's like melted plastic.

-Smut