The working principle of this turbine

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Discussion Overview

The discussion revolves around understanding the working principle of turbine blades, particularly in the context of gas and steam turbines. Participants explore the aerodynamic and mechanical aspects of turbine design, including the roles of impulse and reaction principles in blade function.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about the working principle of closely packed turbine blades, questioning the role of aerodynamic lift and suggesting that the blades resemble airfoils.
  • Another participant identifies the blades as part of a turbine disk rotor, noting the absence of outer stator blades in the video referenced.
  • A question is posed regarding whether the rotor operates on an impulse or reaction principle.
  • One participant suggests viewing the blades as a series of curved convergent or divergent nozzles that manipulate fluid velocity rather than as traditional airfoils, referencing the velocity triangle concept.
  • A participant cites a principle from fluid dynamics related to the moment of momentum and angular momentum flux in control volumes, linking it to turbine operation.
  • A summary reiterates the initial confusion and introduces the idea of hybrid blades that combine impulse and reaction designs, explaining their respective advantages in different parts of the turbine.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the working principle of the turbine blades, with multiple competing views on the nature of the blades and their operational mechanics remaining present throughout the discussion.

Contextual Notes

Some assumptions about the definitions of impulse and reaction turbines may not be fully articulated, and the discussion lacks resolution on the specific mechanics of the blades in question.

T C
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TL;DR
Found a video on net and from the video, the working principle that will rotate the turbine can't be understood properly. Want to know how the blades are working.
Found this video on net, but was unable to understand the working principle of the blades. The blades are very much closely packed and that means aerodynamic lift is simply useless here. But, from the video, it seems that the blades are like airfoils. That's why want to know the working principle behind the blades that will rotate the turbine.
 
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Ok. But, what's the driving principle of this rotor. Is it an impulse type turbine or reaction?
 
T C said:
The blades are very much closely packed and that means aerodynamic lift is simply useless here. But, from the video, it seems that the blades are like airfoils. That's why want to know the working principle behind the blades that will rotate the turbine.
It might be more helpful to view it as a succession of curved convergent or divergent nozzles that accelerate or decelerate the fluid (depending if you want a turbine or a compressor) rather than a succession of airfoils. Look for velocity triangle.

Example of a "curved divergent nozzle" where velocity goes from ##W_1## to ##W_2##:

60aab091be25fd85eeac62550%2Fgeschwindigkeit-4-data.jpg

The concept of a "curved nozzle" might be clearer on a centrifugal compressor (or turbine when rotating in reversed):

com%2Fwp-content%2Fuploads%2F2010%2F10%2Fimage0013.gif
 
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T C said:
TL;DR Summary: Found a video on net and from the video, the working principle that will rotate the turbine can't be understood properly. Want to know how the blades are working.

Found this video on net, but was unable to understand the working principle of the blades. The blades are very much closely packed and that means aerodynamic lift is simply useless here. But, from the video, it seems that the blades are like airfoils. That's why want to know the working principle behind the blades that will rotate the turbine.
From what I'm seeing, they're using hybrid blades. Hybrids use impulse blade design closer to the root and reaction blade design closer to the tip.

Impulse blades are like a classic Pelton turbine design, where you're simply redirecting the flow and getting your force from the flow turning. Reaction blades use the turning force and the velocity changes to produce their force. By mixing the two, you get a mix of their best attributes where they're needed most. The strength and starting torque of the impulse blades at the root and the efficiency and light weight of the reaction blades near the tips.
 
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