Pressure calculation for internal problem using 3D panel method
 

Hi everyone,
I have been developing a simple 3D panel code from scratch. The code is using vortex ring panels, iterative solving of the wake etc. The method works reasonably well for external flow, I started with simple objects, then wings, then a propeller, but the main goal is a water turbine in a turbine case (internal flow) with high pressure drop between inlet and outlet. I calculated the pressure acting on panels as -0.5*density*velocity^2 and then realized this can't be right for this type of problem, where total pressure doesn't stay constant, as in external aerodynamics but drops from inlet to outlet. I can calculate the total pressure drop from the mechanical energy extracted by the turbine but I would like to get the cp distributions etc...

What is the correct approach to calculating the static pressure on the blade surface?

Any help would be highly appreciated

Pressure calculation
 

Hi,
I will try to formulate my problem more generaly.

I have potential flow solver that will give me the flow field around a rotating turbine blade. How to calculate the pressure at the blade surface, when there is mechanical energy being extracted?

Thanks for any clues,

Vitek