Investigation of Wind Loads between Offshore Wind Turbine Joints with Semi-Submersible Floats Using Wind Tunnel Testing and Computational Fluid Dynamics Methods

This study investigates and analyzes the connection between the wind turbine and semi-submersible platform due to the wind load the wind turbine receives using the wind transmission test method and CFD simulation. In wind tunnel test, the Reynolds number plays an important role in affecting the lift coefficient (CL) and drag coefficient (CD) causing limitation of test model size. Testing at wind speeds ranging from 5 m/s to 15 m/s resulted in Reynolds Numbers (RN) ranging from 4×105 to 1.2×106. The analysis of RN reveals that CL exhibits greater fluctuations with changes in RN compared to CD, which remains relatively stable. Both testing and CFD simulations show that lift force (FL) and drag force (FD) increase with wind speed, with discrepancies of approximately ±10.65% for FL and ±10.99% for FD between the two methods. These differences may be attributed to the transition from laminar to turbulent flow or variations in boundary conditions. CFD visualization at the maximum wind speed of 15 m/s shows that the maximum deformation occurs at the turbine blade tips, measuring 6.95×105 mm, highlighting the importance of a robust design to prevent structural failure and maintain turbine efficiency. Stress distribution peaks at the base of the turbine tower, emphasizing the need for high-strength materials and appropriate joint designs. This study provides valuable insights for designing more efficient and durable offshore wind turbines. Further research with varied wind conditions and more complex models is recommended to enhance the comprehensiveness of the findings.