The potential applications of twin vertical axis wind turbines (VAWTs) in oceanic wind energy harvesting have drawn increasing attention. Previous researches have focused on the influence of relative location, rotational direction, tip speed ratio, etc. on the power output of this system. However, limited studies have been done to uncover the effect of pitch angles on their aerodynamic performance, especially under staggered arrangements where the blade-vortex interaction remarkably occurs. In the current study, the methods of computational fluid dynamics are used to simulate the changes of power coefficients of the twin staggered H-rotors with their pitch angles. With a relative distance of 1.6 times diameter and a relative angle of 30 $°$, the rotors are operated at the optimal tip speed ratio in a co-rotating direction. Totally 49 cases are conducted to investigate the pitch angle range from −6° to 0° in both rotors. It is found that the changes in pitch angle of the target rotor will affect the performance of itself and the other rotor with fixed pitch angle. Within the specified pitch range, due to the influence of the other rotor, the largest difference in power performance reaches 4.79% for the upstream rotor, and 7.04% for the downstream one. In addition, the aerodynamic mechanism is comprehensively analysed through the comparisons among velocity, vorticity and pressure fields. The findings of the current study is helpful to provide suggestions for the design of twin-VAWT system.

双垂直轴风力涡轮机（VAWT）在海洋风能收集中的潜在应用越来越受到关注。以往的研究主要集中在相对位置、旋转方向、叶尖速比等对系统功率输出的影响。然而，已经进行了有限的研究来揭示桨距角对其气动性能的影响，特别是在叶片-涡流相互作用显着发生的交错布置下。本研究采用计算流体动力学的方法来模拟双交错H旋翼的功率系数随桨距角的变化。相对距离为直径的 1.6 倍，相对角度为 30$°$，转子在同向旋转方向上以最佳叶尖速比运行。总共进行了 49 个案例来研究两个转子中从 -6° 到 0° 的桨距角范围。研究发现，目标转子桨距角的变化会影响其自身和其他固定桨距角转子的性能。在规定的螺距范围内，由于另一旋翼的影响，上游旋翼的动力性能差异最大为4.79%，下游旋翼为7.04%。此外，通过对速度场、涡量场和压力场的比较，对气动机理进行了综合分析。本研究结果有助于为双VAWT系统的设计提供建议。