-4

Given the compressor section of the engine needs to move much faster and given the larger the blade, the larger the tip speed, would larger compressor blades produce more thrust and therefore better efficiency?

If not, what limits their tip size? Is it the torque of the hot sections of the engines, or to prevent a stall or flameout at the hot sections of the engines?

Pondlife
  • 71,714
  • 21
  • 214
  • 410
securitydude5
  • 8,529
  • 12
  • 57
  • 111
  • 7
    I would seriously recommend you attend aeronautical engineering classes or at least invest the time and read relevant text books. That would answer almost all your questions asked throughout the last weeks. I‘m sure you have good reasons and great ideas to feed all your questions, but what comes across to us readers/participants on this site is astonishingly similar to my five-year-old being let loose on aeronautical engineering - seemingly random, quick-fire questions without any background information given or own workings, let alone research demonstrated. I’m sure you are capable of more! – Cpt Reynolds Mar 02 '18 at 15:56

1 Answers1

2

enter image description here
(wikimedia.org)

The reason is geometry. Consider the image above for an industrial gas turbine (best image I found that will illustrate my point). If you change the blade chord to make it bigger to have fewer blades, they will have an extreme angle of attack and will end up like a wall.

If you maintain the same angle of attack and increase the chord, the disk will be a lot thicker, resulting in a very long engine. And just like delta wings, a deep chord's benefit is only viable at low speed (think Concorde wing-root).

So the high aspect ratio (thin blades) is the choice for an efficient engine. Also the bigger the blade, the much stronger its mounting needs to be (in case you want to try it).

I'm not sure if there's a typo in "the larger the blade, the larger the tip speed." But no, we've covered that before in case you meant the span. The larger the diameter, the slower the RPM, but the tip speed remains more or less the same.

  • So in essence compressor blades have a maximum efficiency speed though they need to be faster than the fans and establishing a efficiency maximising ratio between the two is the optimum and most ideal for the non geared turbo fan – securitydude5 Mar 05 '18 at 13:12