The vortex ring thruster (VRT) is a propulsion system mimicking the propulsive technique of Mollusca, such as squids and jellyfish. VRT’s acknowledged advantages include low noise generation, delicate attitude control, and precise maneuverability. However, due to the low propulsion efficiency, its application is limited to low-speed unmanned underwater vehicle (UUV) only. In the present study, the propulsion performance evaluation of Coanda vortex ring thruster (CoVoRT) with different curvature was performed to examine the application of CoVoRT. The flows around the typical VRT and CoVoRT were analyzed using SNUFOAM, which was open-source toolkit CFD code based on the OpenFOAM. For computational validation, the CFD results for the flow around VRT were compared with the previous simulations and experimental results. Then propulsion performance of VRT and CoVoRT was compared in terms of the PPEI, and the vortex ring formation process. The results showed that CoVoRT"s PPEI is approximately 50% higher than that of VRT. Also, the vortex ring formation by CoVoRT was enhanced by the Coanda jet.