## 1 Introduction  
The International Maritime Organization (IMO) institutionalized the Energy Efficiency Design Index (EEDI) in 2013 to reduce the greenhouse gas (GHG) emissions of ships and is strengthening regulations. The goal is reducing the annual amount of GHG generated by international shipping by 2050 by at least 50% compared to 2008, so ships built after 2025 should reduce the amount of GHG by 30% compared to the standard value [1]. Methods to reduce the EEDI to satisfy the regulations include reducing the CO\({}_{2}\) conversion factor, the designed fuel consumption rate, or the designed engine power rate, as well as increasing the designed speed and the designed capacity volume [2]. In phase 2, the EEDI should be reduced by 20% compared to the initial value. The EEDI regulation could be satisfied by reducing engine power obtained through slow operation. In phase 3, additional technology development is required to improve fuel economy. In order to satisfy the currently strengthened EEDI regulations, many studies are being conducted to reduce the required power of ships. In this study, attention is paid to a method of increasing propeller propulsion efficiency as a way to increase a ship's efficiency. In order to increase the efficiency of propellers, we tried to apply the Coanda effect to screw propellers that are currently used in most ships. The Coanda effect refers to a phenomenon in which the jet flows along the curvature of a curved surface. When the jet flows along the curved surface, the flow direction changes to induce the flow direction of the surrounding fluids, and a force is generated in the opposite direction of the fluid flow by the law of action and reaction. We devised a propeller that converts the force generated through the Coanda effect into the thrust of the propeller. The Coanda effect is currently widely applied in the aeronautical field. [PERSON] et al. [3] confirmed that the jet on an airfoil surface is effective in increasing the lift and controlling stall by designing an airfoil surface to allow injection and suction, as well as performingexperiments and a numerical analysis. In addition, after applying a flap and droop nose to the airfoil, the effect of the jet on the airfoil was analyzed through experiments [4; 5] and numerical analysis [6]. Model tests [7] and a numerical analysis [8] were performed using plasma actuators to analyze changes in airfoil performance. [PERSON] et al. [9] compared the behavior of jet injection according to the turbulence model in a circulation control airfoil. In order to apply the Coanda effect to ships, there are many studies in which a hydrofoil is applied. [PERSON] et al. [10] designed a hydrofoil capable of jet injection and performed a model experiment in a cavitation tunnel. They showed that the lift increased by up to three times through jet injection. Also, experiments [11] and a numerical analysis [12] were performed by attaching a rotor to the trailing edge of a hydrofoil, and it was found that the lift force was increased by reinforcing the circulation flow as the rotor rotated. [PERSON] et al. [13] designed a three-dimensional Coanda horn rudder, performed experiments and computations, and compared the lift increase in jet flow for various rudder angles. In addition, by incorporating the Coanda effect into a stabilizer fin, the performance of the fin stabilizer was improved by increasing the lift. At the same time, the effect of power reduction was confirmed by comparing the required power with that of a fixed stabilizer fin [14]. According to previous studies, both airfoils and hydrofoils showed the same tendency of increased lift when jet injected from the surface. To apply the tendency of increased lift to a propeller, [PERSON] et al. [15] proposed a hydrofoil shape that not only increases lift during jet injection, but also reduces cavitation compared to a circulation-type shape. In this study, a jet injection propeller was designed based on the research of [PERSON] et al.