The fluid flows from the impeller to the turbine in a clockwise direction. However, as the fluid flows through the turbine, its direction is reversed to a counterclockwise direction.

If the fluid were allowed to return to the impeller in a counterclockwise direction, it would enter the impeller as an opposing fluid flow, which would reduce the pumping efficiency of the impeller. The impeller would have to spend part of the rotational force, or torque, it receives from the engine to redirect the fluid flow.

When the stator redirects the fluid to enter the impeller in a clockwise direction, no torque is wasted. In fact, the redirected fluid actually helps push the impeller, thus multiplying torque.

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