Learning About Air Coupling in Shafts - Diagrams Welcome!

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SUMMARY

The discussion focuses on air coupling between shafts, specifically its application in turbine engines, such as those by Pratt & Whitney. Participants explore the mechanics of air coupling, comparing it to hydrostatic drives and discussing its efficiency. The conversation highlights the concept of energy transfer through axial flow between counter-rotating fans and the role of stationary and rotating blades in turbo-compressors. The need for diagrams and further resources on this topic is emphasized, indicating a gap in available information.

PREREQUISITES
  • Understanding of air coupling mechanics
  • Familiarity with turbine engine design, particularly from Pratt & Whitney
  • Knowledge of turbo-compressor and turbine blade configurations
  • Basic principles of fluid dynamics related to energy transfer
NEXT STEPS
  • Research "air coupling applications in turbine engines"
  • Study "hydrostatic drives vs. air coupling" for efficiency comparisons
  • Examine "counter-rotating blade systems in turbo-compressors"
  • Look for diagrams and technical papers on "energy transfer in axial flow systems"
USEFUL FOR

Engineers, mechanical designers, and students interested in turbine engine technology, fluid dynamics, and energy transfer mechanisms in rotating systems.

Shawnzyoo
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I am trying to learn more about air coupling.
That is the coupling between 2 shafts
I am having a hard time finding any information on the subject matter
does anyone know how these systems work and have any diagrams?
thanks
 
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Maybe it's because I haven't had my coffee yet this morning, but I can't say I have ever seen or heard of an air coupling for shafts. Can you point me to an existing application?
 
Does this have anything to do with concentric counter-rotating shafts?
 
Something like how when you blow one fan into another fan, the second fan's rotors start moving as well? It seems like a very weak sort of coupling... maybe better in more viscous fluids or the other way around? o.O
 
i was reading about this coupling with turbine engines from Pratt & Whitney.
i can't for the life of me find the link right now

but i think mezarashi has described it
 
So it's like a hydrostatic drive without the hydro? Sounds pretty inefficient.
 
Certainly, if one takes an axial flow from one fan and impose it on another fan, the second fan's blade will experience energy/momentum from the flow and start to rotate. That would be expected.

In conventional turbo-compressors and turbines, one normally has a set of stationary blades (stator) and rotating set of blades (rotor). For a very simple turbine or compressor with two stages, one could have counter-rotating blade sets. One can get comparable energy transfer but at reduced rotational speed.

As for hydraulic coupling - automatic transmissions use just that.

In the case of PW, how are the turbine engines suppose to be coupled?
 
Engine spools do, at times, counter rotate to the other. The rotational directions are set up via gas path angles in the rotors themselves. I have not really heard of this as a coupling. The usual mechanical coupling is a curvic coupling. I'll do some seariching around now that you gave a hint to it's application. It would be nice to see the link you are referring to.
 
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