What Happens When An HPT Lets Go (56k Wng)

TobyV · Post by **TobyV** » 10 Jun 2006, 00:16

Dont worry... I'm giving up trying to get into engineering soon and looking at a career in estate agency instead, so I'll revert to speaking in English.

In a nutsell, the gases flowing through the turbine of a modern engine are at somewhere between 1300 and 1900K, thats about 1030 to 1630 deg C, or "very ****ing hot"

. The melting temperature of said blades is often actually lower and they only dont melt because they are cooled by air bled from the compressor and ejected through little holes in the surface of the blade fed by complex passages inside the blade. This air envelopes the blade and protects most of it from the "full brunt" of the flow from the combustion chambers. Factor in that these blades are cast as single crystals (something thats very hard to do) and its really quite amazing stuff and most of the reason why even the likes of Frank Whittle didnt really think that jet engines could ever be built that large, powerful or efficient!

To a large extent, its the materials and manufacturing technology that have really allowed us to build the sorts of engine that power all the wide body jets of today, but if the slightest little defect in the material or manufacturing slips through, you end up with a situation as in the photos on the first page :sad:

Post by **Garry Russell** » 10 Jun 2006, 00:27

And so pushed to the limit it means a re design to get more power out of the engine rather than pumping more fuel in and spinning it faster.

It is amazing that it does go for so long.

Garry

jonesey2k · Post by **jonesey2k** » 10 Jun 2006, 09:55

Ill remember that when I try and make a GT out of a turbo!

VC10 · Post by **VC10** » 10 Jun 2006, 10:34

TobyVickers wrote: In a nutsell, the gases flowing through the turbine of a modern engine are at somewhere between 1300 and 1900K, thats about 1030 to 1630 deg C, or "very ****ing hot" . The melting temperature of said blades is often actually lower and they only dont melt because they are cooled by air bled from the compressor and ejected through little holes in the surface of the blade fed by complex passages inside the blade. This air envelopes the blade and protects most of it from the "full brunt" of the flow from the combustion chambers. Factor in that these blades are cast as single crystals (something thats very hard to do) and its really quite amazing stuff and most of the reason why even the likes of Frank Whittle didnt really think that jet engines could ever be built that large, powerful or efficient!

My GE CF6-80 training manual states that at T.O. the gas temp at the exit from the combustion chanber is 2850 R which I make 1310 C. The temp on exiting the HPT is 1946 R (807 C). By the time the gas has passed though the LPT the temp has fallen to 1333 R (740 C)

Nozzle Guide Vane Cooling

HPT rotor cooling

High Press Turb Stg1 cooling

HPT2 cooling

TobyV · Post by **TobyV** » 10 Jun 2006, 11:26

Hi Paul, I actually wrote a long post last night that explained in words, exactly what your diagrams you've just posted are showing. I decided not to click "submit" eventually though as it might be too boring, too technically worded fo those that dont have a clue what I was on about and too patronising for those that did. A picture says a thousand words, as they say though

TobyV · Post by **TobyV** » 14 Jun 2006, 23:35

http://www.airliners.net/open.file/1059747/L/

Guess this was it...

jonesey2k · Post by **jonesey2k** » 15 Jun 2006, 01:08

TobyVickers wrote:http://www.airliners.net/open.file/1059747/L/

Guess this was it...

LOL! I had the same link copied and was going to post it !