Friction concentric rotating cylinders

[Adrian77]

Hello All,

I am trying to calculate the friction (torque) between two concentric cylinders.
Inside one is roating at 750 rpm, diameter is 826 mm and diametrical clearance is 4 mm.
Outside cylinder is static. Length 98 mm.
I guess it should be quite large but couldn't find any reference.
Maybe you can give some advice or reference.

Thanks in advance.

 

[Adrian77]

I forgot to say that there is sea water in between.

 

[zekeman]

This is a classic hydrodynamic lubrication problem.
Almost any handbook in mechanical engineering will give a nomograph for the problem.