Calculating turbine RPM in a pipe with known air velocity and diameter

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Discussion Overview

The discussion centers around calculating the RPM of a turbine located in a closed pipe, given known air velocity and pipe diameter. Participants explore various factors that may influence the turbine's rotational speed, including resistive torque and blade pitch, while also considering the complexities involved in modeling the lift on turbine blades.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions whether the calculation of turbine RPM can be performed with the given parameters of air velocity and pipe diameter.
  • Another participant suggests that lower resistive torque at the turbine shaft may lead to higher rotational speeds.
  • A participant inquires about the type of turbine, noting that if it is a propeller or fan blade, the pitch of the blades is a significant factor affecting RPM.
  • One participant expresses a desire for a detailed explanation of the calculation process, mentioning the need to consider lift on each blade, the number of blades, and the effects of spinning blades on incoming fluid, indicating challenges in their own modeling efforts.

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus on the calculation method or the factors influencing turbine RPM, with multiple viewpoints and uncertainties expressed throughout the discussion.

Contextual Notes

Participants highlight various assumptions, such as the type of turbine and the influence of blade pitch and resistive torque, but these aspects remain unresolved in the context of the calculation.

matth6197
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Hello,

I am trying to calculate the turbine RPM for a turbine in a closed pipe. I know the air velocity and pipe diameter. Can this be done?
 
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Welcome, @matth6197 !

The lighter the resistive torque or resistance at the shaft of the turbine the higher its rotational speed should be.
 
Is your turbine just a propeller or a fan blade. If so, then the pitch of the blades is the most significant factor in RPM.
 
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I hope somebody posts a detailed answer for how this calculation is done. I am dealing with a similar problem for wind turbines.

I expect you will somehow need to calculate the lift on each turbine blade multiply by the number of them and model it as a circular motion problem. but then you also need to take into account the change of lift per blade due to the fact the blade will spin, (whereas it was stationary at first) and also the effects of the spinning blades on the incoming fluid as well. All issues currently beyond my modelling abilities
 

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