<p>Experimental studies were conducted to investigate the flow velocity distribution and turbulence intensity in a vortex settling tank (separator) and to examine changes when the flow rate is doubled. Two experiments were performed, each using a different flow rate through the tank. Variations in the turbulence structure were evaluated at two depths using measurements of instantaneous flow velocities obtained with a three-component acoustic Doppler velocimeter. The resulting changes in velocity and turbulence intensity, along with their spatial distributions within the settling tank, were analyzed. The findings showed that doubling the flow rate led to a threefold increase in average flow velocity near the tank walls, a twofold increase in turbulence intensity in the same region, and the expansion of zones with elevated local turbulence. Within these zones, the gradients of turbulence intensity rose substantially more than in other areas. The highest turbulence intensities were observed on the left side of the tank near the outlet deflector. Overall, the identified changes in the turbulence structure negatively impact the tank’s performance, as they significantly increase flow velocity and turbulence intensity; however, this does not result in a significant decrease in the tank’s efficiency.</p>