On account of the specific angle of the stator blades, the fluid flows again in a slower amount, which multiplies the torque. Inside of a torque converter there are actually at least 3 rotating components: the impeller, that's mechanically pushed with the key mover; the turbine, which drives the load; https://torqueconverterclutch07529.mybuzzblog.com/13695397/considerations-to-know-about-torque-converter-clutch