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Forum: Tech Log
20th Apr 2013, 15:26
Replies: 148
Views: 79,664
Posted By goarnaut

Thrust Distribution in a Jet Engine...

Tom...please refer to my previous posts in this thread...I have even drawn little sketches to illustrate the physics...I do have a degree in aerospace engineering and I work in the industry...

It...
Forum: Tech Log
28th Nov 2012, 05:16
Replies: 148
Views: 79,664
Posted By goarnaut

Supersonic Speeds Inside Engine...

Brian...yes the tip speed of the compressor and fan will almost always be supersonic in a modern turbine engine...typically from M1.2 to M1.7...even a turbocharger compressor will go supersonic at...
Forum: Tech Log
27th Nov 2012, 18:51
Replies: 148
Views: 79,664
Posted By goarnaut

Turin, Here is a smaller version

http://i49.tinypic.com/sdl00h.jpg
Forum: Tech Log
27th Nov 2012, 18:47
Replies: 148
Views: 79,664
Posted By goarnaut

Peter...now you are mixing and matching accounting methods...

Yes...ram drag is what we subtract from the gross thrust...ram drag is freestream speed (aircraft speed) times mass flow...so that is why thrust = mass flow * (jetpipe exit speed freestream...
Forum: Tech Log
27th Nov 2012, 18:12
Replies: 148
Views: 79,664
Posted By goarnaut

And just one more thought...

Clive mentioned that the engine structural designers were probably the only ones calculating the component thrust and drag...you can be sure that is the very first thing they did...


In order...
Forum: Tech Log
27th Nov 2012, 17:59
Replies: 148
Views: 79,664
Posted By goarnaut

Crabman...maybe the word thrust is making it hard for you...

If you prefer... think of the inlet making a forward force...that's all it is...and that force is very real..the mechanism of it is that the diverging duct shape decreases flow speed and increases...
Forum: Tech Log
26th Nov 2012, 21:16
Replies: 148
Views: 79,664
Posted By goarnaut

Great to Hear Pilot Perspective

NW1...it's good to hear from you...your numbers fill in some blanks...How long did it take to reach cruise altitude...?...


Crabman...the inlet is not transferring the thrust force from the...
Forum: Tech Log
26th Nov 2012, 10:07
Replies: 148
Views: 79,664
Posted By goarnaut

Thanks...Clive...

Okay...the numbers are starting to come together like they should...

I made a math boo-boo in calculating cruise mass flow...but now I get ~177 lb...oh well...that's in the ballpark at least...
...
Forum: Tech Log
26th Nov 2012, 05:47
Replies: 148
Views: 79,664
Posted By goarnaut

Peter...

The flow going into the compressor or fan is going to be at its design speed as long as the engine is turning at its design rpm...even when the airplane is standing still on the ground the engine...
Forum: Tech Log
25th Nov 2012, 17:56
Replies: 148
Views: 79,664
Posted By goarnaut

Here is the Sketch Hope It Works

http://i46.tinypic.com/1w4n8.jpghttp://tinypic.com/r/1w4n8/6
Forum: Tech Log
25th Nov 2012, 17:42
Replies: 148
Views: 79,664
Posted By goarnaut

Trying to Post A Sketch ut It Won't Let Me...

The math is quite straightforward and can be found in any good engine text or fluid mechanics text...but that does not help us understand the physical principles behind it...


I have already...
Forum: Tech Log
25th Nov 2012, 10:22
Replies: 148
Views: 79,664
Posted By goarnaut

Thanks for those numbers, Clive...

I had estimated the compressor inlet area at ~1 m^2...based on the engine static mass flow of ~450 lb/s...and an assumed inlet Mach of 0.5...


Seeing as cruise mass flow is a lot less...perhaps...
Forum: Tech Log
25th Nov 2012, 04:53
Replies: 148
Views: 79,664
Posted By goarnaut

Tupolev Tu144

It was mentioned earlier that the Tu144 did not supercruise...and that Soviet designers never did solve the technical challenges in creating an efficient engine inlet...

In the spirit of fairness...
Forum: Tech Log
24th Nov 2012, 15:32
Replies: 148
Views: 79,664
Posted By goarnaut

Interesting Stuff

Clive...thanks for chipping in with some very interesting info...


Always good to hear from one of the design team members...just curious about a couple of things...what was the mass flow per...
Forum: Tech Log
21st Nov 2012, 11:27
Replies: 148
Views: 79,664
Posted By goarnaut

Intake Thrust is Due to Impulse

I realize this thread is two years old...but I just came across it and would like to clear up some of the misconceptions here about what causes the high amount of thrust produced by the Concorde...
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