Spool systems in compressors

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  • #26
minger
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Due to the momentum and viscosity of water, they do not need to.
At which point, it is no longer a reaction turbine, it's an impulse turbine. They can use high head application, but like you said, you're using water momentum, not pressure to drive the blades. Because the wheel is spinning at 1/2 speed of the water jet, the actual force on the blades is not astonomical.


Well this is a rather inane remark. Since you chose not to address the science/physics/engineering issue directly,
Simply saying "It can be done" doesn't either.


I'm flummoxed by your, Fred's, and others' errant belief that I am in any way proposing single-stage designs, particularly given my oft-repeated "possible, but not practical" mantra.
There's a big difference between not practical and not doable. There is reason behind one. It's not practical to drive a Hummer. However, if I have the money to do so and feel the need to look cool, why the hell not?

Could there be reason for a single-stage axial machine like you're describing? Sure, perhaps there are packaging concerns, maybe a single-stage can cost less than multi for a limited life application. However, if one of our customers came to us and asked for such a machine, we would respecfully decline, and not because it's not practical.

Well, in all honesty, we'd probably take the cabbage and then just not deliver (either on time or meeting goals). You know, the usual.
 
  • #27
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There are numerous design constraints such at the blade tip speed and the speed of sound in the compressed air. The back pressure on a single stage with a compression ratio of 20:1 would be enormous and the rotation of the flow would seem to be problematic.
At 280 psi, it would have to be driven beyond mach. I never claimed one was ever designed, much less built. I merely stated it was possible.
 
  • #28
Astronuc
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At 280 psi, it would have to be driven beyond mach. I never claimed one was ever designed, much less built. I merely stated it was possible.
Please demonstrate that it is possible, or at least provide the equation for the compression ratio of a single compressor stage for an axial flow.
 
  • #29
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Please demonstrate that it is possible, or at least provide the equation for the compression ratio of a single compressor stage for an axial flow.
(Sigh), it's beyond my dusty, 25-year-old degree. But it wasn't beyond the talents of my propulsion instructor who used it as an example of what's possible, but not practical.
 

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