The occurrence of gas-entraining vortices in pump inlets of cooling water circuits poses a great threat for the reliable operation of power plants, water turbines and chemical reactors, due to the unpredictable operating behavior caused by gas accumulation in pumps and valves and due to long-term damage caused by cavitation. Since the formation and resulting strength of gas-core vortices depends in large parts on the circulation, caused by the pump intake geometry and on parameters of different scalability, the prediction of vortex development remains challenging for industrial scales. Therefore, the focus of this thesis is on the experimental investigation of induced circulation on the vortex formation in a large scale research setup under critical inflow conditions. For this purpose, vortex formation has been studied for varying circulations, submergence depths and intake geometries within a 50 m3 experimental vessel at the Hamburg University of Technology.