# Fluid mechanics of turbines

1. Jun 6, 2013

### hihiip201

Hi all:

I have a question regarding the fluid mechanics of turbine, both impulse and reaction turbines.

I have searched many sites , including my fluid mechanic textbook, and yet I still don't quite understand the physics behind a turbine.

Impulse turbine is a bit easier to understand as I can use plain newtonian mechanics (2nd law) to understand the transfer of energy and momentum.

But for a reaction turbine, although it is essentially Newton's third Law, I am stuck on how to analysis the pressure, velocity and work done on the rotor using strictly fluid mechanics principles (Bernoulli equation etc). I am fully aware that they are still just Newtonian's mechanics, but I would like to understand it in terms of fluid mechanics concepts - and then relate it back to newtonian's mechanics.

When I took fluid mechanics , all we were taught is to treat the turbine in a fluid flow a "black box" the exert a force in the fluid flow going past it when using Navier Stoke's equation because my professor was more concern with us knowing the idea of the integral and differential momentum equations.

thank you

2. Jun 6, 2013

You can't use Bernoulli's equation. Work is being done by the fluid.

3. Jun 6, 2013

### SteamKing

Staff Emeritus
4. Jun 6, 2013