本文研究目的是使用開源模擬軟體OpenFOAM中interFoam求解器模擬潮汐渦輪發電機在固定水流中不同tip speed ratio的尾流情形，固定水流流速為0.4m/s，為達成6種tip speed ratio之比較，渦輪使用不同轉速來模擬不同tip speed ratio之情況，轉速分別為8、9.33、10.4、10.67、12、13.33 rad/s。該渦輪發電機的直徑為0.3米，葉片使用S822葉片，其旋轉平面距離入口的距離為1.5米，距離出口的距離為4.5米。此外，渦輪發電機的旋轉軸距離底部為1米，距離頂部為0.6米，整體水深為0.3米。
模擬結果以power coefficient與StarCCM以及實驗值做比較，觀察OpenFOAM之準確性。再將不同tip speed ratio之尾流作比較分析，分析物理量包括，streamwise velocity、velocity deficit、turbulence intensity、momentum flux，在C_p值的驗證發現在TSR=3.9、4的地方OpenFOAM及StarCCM都能與實驗值相符，且在TSR=3的地方OpenFAOM有比StarCCM更好的預測值，但TSR=4.5、5時，OpenFOAM就相對不準確。
從streamwise velocity以及velocity deficit可以看出此次模擬的渦輪機因為紊流強度過小，都有回流的情況發生，且渦輪機轉速越高，回流的情況越為明顯。且因為此原因，造成不同TSR的尾流並沒有明顯差異。
另外，由TI的contour可以發現尾流會受到自由液面的影響，靠近水面的地方會有比較大的TI值。 最後，在momentum flux的結果可以看到葉片尖端後方的動量皆往葉片中心後方做傳遞，並且傳遞的值大小約為10^(-4)，這個值對於動量傳遞是非常小的，推測此結果是因為水的黏度相較於空氣的黏度大，因此會影響動量的傳遞，才會造成動量通量小的原因。

The aim of this research is to simulate the wake characteristics of tidal turbine generators at different tip speed ratios (TSR) in fixed water flows using the interFoam solver in the open-source software OpenFOAM. The fixed water flow speed is set to 0.4 m/s. To compare across six different TSRs, the turbine is operated at different rotation speeds to simulate different TSR scenarios, specifically at 8, 9.33, 10.4, 10.67, 12, and 13.33 rad/s. The turbine has a diameter of 0.3 meters, and uses S822 blades. The rotational plane of the turbine is 1.5 meters from the inlet and 4.5 meters from the outlet. Additionally, the rotation axis of the turbine is 1 meter from the bottom and 0.6 meters from the top, with an overall water depth of 0.3 meters.
Simulation results are compared with the power coefficient from StarCCM and experimental data to examine the accuracy of OpenFOAM. The wake characteristics at different TSRs are then analyzed and compared, with the physical quantities analyzed including streamwise velocity, turbulence intensity, and momentum flux. It was found that OpenFOAM and StarCCM both align well with experimental data at TSRs of 3.9 and 4. Furthermore, OpenFOAM provides better predictions than StarCCM at a TSR of 3, but is less accurate at TSRs of 4.5 and 5.
From the streamwise velocity , it can be seen that due to the small turbulence intensity, backflow occurs in the turbine simulated in this study. Furthermore, the higher the turbine speed, the more pronounced the backflow. This situation has led to no significant difference in the wake between different TSRs.
Additionally, from the turbulence intensity contour, it can be seen that the wake is influenced by the free water surface, with larger turbulence intensity values near the water surface.
Finally, in the momentum flux results, the momentum behind the blade tips is transferred towards the back of the blade center, and the transferred value is approximately 〖10〗^(-4). This value is very small for momentum transfer, suggesting that the larger viscosity of water compared to air may affect momentum transfer, resulting in small momentum flux.

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