Fanno flows and Energy generation

Fanno flows are a very interesting phenomenon in fluid dynamics: the flow (steady, 1D, adiabatic) is moving in a pipe where friction forces are not negligible. Due to the second law of thermodynamics, if the inlet flow is subsonic, the presence of friction in this case decreases the flow’s temperature and increases its velocity: the Mach number increases as well. The opposite happens if the inlet flow is supersonic. Both will reach Mach 1 (choke condition).
My question is: could we build (or, does it already exhist…) a long pipe in which the frictional choke is not reached and use turbines to produce energy from the flow? Would this violate the increase in entropy?

Thanks in advance.