The fan is probably not ideal, the blades are small in relation to the diameter but it should work in some way.
The whole thing looks far too large for your water supply so again not ideal.
With that supply pipe, if you can get it to run full with full head you will only need a small nozzle area so don't expect to use much of the width. Your nozzle will also probably only span one blade if you want to keep the velocity up. I don't know how much energy you will reclaim on the second stage but with the large diameter you have a reasonable chance of it reaching the second stage at some sort of sensible angle.
I think the Banki is somewhat misunderstood and many things I have seen seem far too big for the volume of water supplied. With your little supply pipe I suspect something reasonably proportioned would use a rotor about 1/4 the width and diameter.
Your nozzle needs to be small enough to convert the pressure energy in the pipe into velocity so its throat area will be well below the supply pipe area.
Don't forget it is not a waterwheel, it is a turbine. Look at some of the pictures of the Ossberger ( spelling?) to get a realistic idea of the nozzle and how it conforms to the rotor surface.
Flux
