A series of experimental tests on flow-induced motion (FIM) and energy conversion of two rigidly coupled triangular prisms (TRCTP) in tandem arrangement were conducted in a recirculating water channel with the constant oscillation mass m_osc. The incoming flow velocity covered the range of 0.395 m/s ≤ U ≤ 1.438 m/s, corresponding to the Reynolds number range of 3.45 × 10⁴ ≤ Re ≤ 1.25 × 10⁵. The upstream and downstream triangular prisms with a width of 0.1 m and length of 0.9 m were connected by two rectangular endplates. Seven stiffness (1000 N/m ≤ K ≤ 2400 N/m), five load resistances (8 Ω ≤ R_L ≤ 23 Ω), and five gap ratios (1 ≤ L/D ≤ 4) were selected as the parameters, and the FIM responses and energy conversion of TRCTP in tandem were analyzed and discussed to illustrate the effects. The experimental results indicate that the “sharp jump” phenomenon may appear at L/D = 2 and L/D = 3 significantly, with substantially increasing amplitude and decreasing oscillation frequency. The maximum amplitude ratio in the experiments is A*_Max = 2.24, which appears after the “sharp jump” phenomenon at L/D = 3. In the present tests, the optimal active power P_harn = 21.04 W appears at L/D = 4 (U_r = 12.25, K = 2000 N/m, R_L = 8 Ω), corresponding to the energy conversion efficiency η_harn = 4.67%.

The tension legs are the essential parts of the tension legs platform-type (TLP-type) floating offshore wind turbine (FOWT) against the extra buoyancy of FOWT. Therefore, the TLP-type FOWT will face the risk of tension leg failure. However, there are seldom analyses on the hydrodynamic response and tension leg failure performance of FOWT with inclined tension legs. In this paper, a hydrodynamic model was established using three-dimensional hydrodynamic theory and applied in the motion response and tension analyses of FOWT with conventional and new tension leg arrangements on Moses. The influence of draft and tension leg arrangement on the performance of FOWT with inclined tension legs were studied. The optimum draft was the height of the column and lower tensions were obtained for the new tension leg arrangement. Moreover, the tension leg failure performance of FOWT with inclined tension legs was evaluated under different failure conditions. The results illustrated that the FOWT with the new tension leg arrangement can still operate safely after one tension leg fails.

Multiple compartments exist inside the composite bucket foundation (CBF), and each compartment can be adjusted individually to adjust air pressure. The CBF tilts and sinks because of environmental load during offshore transportation, and the differential air pressure between compartments produces unbalanced forces and deforms the bulkhead structure. Considering different influencing factors, the finite element calculation method was used to analyze the law of the allowable differential air pressure during offshore transportation. The results showed that the effect of differential air pressure on the deformation of the bulkhead is the key factor for controlling the differential air pressure. The maximum allowable differential air pressure increases linearly with increasing external draft and bulkhead thickness during the offshore transportation of the CBF and is more sensitive to the change in external draft. Finally, the optimal thickness of the bulkhead for different CBF conditions was obtained, providing technical support for engineering safety and economy.