Auxiliary lift and/or thrust on a compound helicopter can introduce complex aerodynamic interactions between the auxiliary lift and thrust components and the main rotor. In this study high-fidelity computational fluid dynamics analyses were performed to capture the various aerodynamic interactions which are occurring for the Airbus RACER compound helicopter, featuring a box-wing design for auxiliary lift in cruise and wingtip-mounted lateral rotors in pusher configuration for auxiliary thrust in cruise and counter-torque in hover. Although the study was limited to a specific geometry, the effects and phenomena are expected to be to some extent applicable in general for compound helicopters and wingtip-mounted rotors in pusher configuration. A quantitative indication of the aerodynamic interaction effects could be established by leaving away different airframe components in the simulations. The downwash of the main rotor was found to cause a small negative angle of attack in cruise for the wings and lateral rotors and impinged directly on the lateral rotors in hover, resulting in moderate to very significant sinusoidally varying blade loading. The wing increased lateral rotor propulsive efficiency in cruise through its wingtip rotational flowfield and to a lesser extent through its wake. An upstream effect of the lateral rotors on the wing loading was also found. In hover the wing caused a net increase in left lateral rotor thrust as the deflection of the main rotor flow towards the rotor resulted in a local thrust decrease and the low momentum inflow to the rotor from the wake of the wing resulted in a local thrust increase. A small thrust decrease for the right lateral rotor was found due to the wing disturbing its slipstream as this rotor produced reversed thrust. In general, very significant aerodynamic interaction effects can be expected when a main rotor, lateral rotors and wing are in proximity to each other.

复合式直升机上的辅助升力和/或推力会在辅助升力和推力组件与主旋翼之间引入复杂的空气动力学相互作用。在这项研究中，进行了高保真计算流体动力学分析，以捕捉空中客车RACER复合直升机发生的各种空气动力学相互作用，其特点是采用了箱翼设计，用于巡航辅助升力，机翼安装在辅助推进器上的侧向旋翼推力巡航和悬停反扭矩。尽管研究仅限于特定的几何形状，但预期效果和现象在某种程度上可普遍应用于复合直升机和安装在推进器结构中的机翼安装式旋翼。可以通过在模拟中保留不同的机身部件来建立空气动力学相互作用效果的定量指示。发现主旋翼的下冲会在巡航过程中对机翼和侧旋翼产生较小的负攻角，并在悬停时直接撞击在侧旋翼上，从而导致叶片载荷呈中度到非常大的正弦变化。机翼通过其翼尖旋转流场并在其尾流时较小程度地提高了侧向旋翼推进效率。还发现了侧向旋翼对机翼载荷的上游影响。在悬停时，机翼导致左旋翼侧向推力净增加，这是因为主旋翼流向旋翼的偏转导致局部推力减小，而从机翼尾流向旋翼的低动量流入导致局部推力增加。由于机翼干扰了其滑流，因此右侧旋翼的推力减小很小，因为该旋翼产生了反向推力。通常，当主旋翼，横向旋翼和机翼彼此靠近时，可以预期到非常显着的空气动力相互作用效果。