Why is there no entropy change in fluid as it passes through a turbine, if the temperature of the fluid drops through the turbine? Lower temperature means lower entropy, so what gives? T-s diagram doesn't make sense. How can entropy even remain the same with temperature changing?

I've read several explanations that didn't go really into detail about transfer vs generation of entropy, and ordered (work) vs disordered (heat) energy. My class never mentioned either of those. Could anyone explain why entropy only ever changes with heat flow, at least in the case of a simple rankine cycle?