With all the a few-passage torque converter, two passages are used for transmission oil (ATF) flow through the torque converter and for clutch cooling, while the 3rd passage is employed independently to manage the lock and unlock in the clutch. As it hits the turbine blades, the turbine begins rotating. https://torqueconverterclutch30627.digitollblog.com/34065372/torque-converter-clutch-fundamentals-explained