The result from a multi-objective optimization on the outlet diffuser angle of the tidal turbine is presented with a focus on the turbine efficiency and cavitation. This study is the first to investigate the impact of the diffuser angle on the diffuser augmented tidal turbine in performance and cavitation inception. The 1/2 scale model was designed with three blades based on NACA 4616 airfoil. Seven diffuser angles were varied from 10.43° to 35.97° in tidal current velocity around 0.7 m/s. The standard k−ε turbulence model and the multiple reference frame motion were conducted in steady-state for the computational analysis with Tip Speed Ratio (TSR) ranged from 1 to 5. It was shown that the diffuser angle strongly influences the turbine performance and cavitation inception. The maximum power coefficient was found at the largest diffuser angle as more space for the turbine to rotate leads to a higher pressure drop, which involves the current velocity change extracted to the torque of the rotor. However, the highest cavitation was also found at the largest diffuser angle since a higher-pressure drop increases the cavitation number. By multi-objective optimization using the GA-ANN method supported by TOPSIS, it was concluded that the optimum design of the tidal turbine was owned by a diffuser angle of 20.04°.

潮汐涡轮机出口扩散角的多目标优化结果以涡轮机效率和气蚀为重点。这项研究是第一个研究扩压器角度对扩压器增大潮汐涡轮机性能和空化开始的影响的方法。1/2比例模型是基于NACA 4616机翼设计的带有三个叶片的设计。七个扩散角在大约0.7 m / s的潮流速度下从10.43°到35.97°不等。标准k - ε在稳态下进行湍流模型和多参考系运动以进行叶速比（TSR）为1到5的计算分析。结果表明，扩压器角度对涡轮性能和气蚀开始有很大影响。在最大的扩散角处发现了最大功率系数，这是因为涡轮机旋转的空间更大，导致压降更高，这涉及到提取到转子转矩的当前速度变化。然而，由于较高的压降增加了空化次数，因此在最大的扩散角处也发现了最高的空化。通过使用TOPSIS支持的GA-ANN方法进行多目标优化，得出的结论是，潮汐涡轮机的最佳设计归因于20.04°的扩散角。