涵道螺旋桨多工况设计

单一工况下设计的涵道螺旋桨通常不能满足垂直起降飞机的多工况高效需求。基于叶素动量理论可以开展涵道螺旋桨多工况设计,其关键在于不同工况下螺旋桨拉力占比、修正来流速度的计算。在无螺旋桨几何的情况下,采用动量源方法对涵道拉力进行估算,提出了修正来流速度的计算方法,基于最小能量损失原则建立螺旋桨几何,采用多重参考系方法进行耦合计算流体力学（Computational Fluid Dynamics, CFD）修正,得到单一工况下弦长扭转角关系、螺旋桨拉力占比以及修正来流速度。通过改变设计升力系数及转速,使不同工况下涵道螺旋桨的弦长及扭转角相匹配。分析结果表明,动量源方法计算的涵道拉力占比较大,来流速度修正方法可减少相同工况下耦合CFD求解计算量。多工况设计可有效提高涵道螺旋桨的综合效率。

Design of Ducted Propeller under Multi-working Conditions

The ducted propeller designed for a single working condition usually cannot meet the high efficiency requirements of vertical take-off and landing aircraft under multi-working conditions. The key to the multi-working condition design of the ducted propeller based on the blade element momentum theory lies in the calculation of the propeller thrust ratio and the correction of the inflow velocity under different working conditions. In the absence of propeller geometry, the momentum source method is used to estimate the duct thrust, and a method for correcting the inflow velocity is proposed. Based on the principle of minimum energy loss, the propeller geometry is established and the multiple reference frames method is used for coupled CFD（Computational Fluid Dynamics） correction to obtain the relationship between chord length and twist angle, propeller thrust ratio and corrected inflow velocity under a single working condition. By changing the design lift coefficient and rotational speed, the chord length and twist angle of the ducted propeller can be matched under different working conditions. The design results show that the momentum source method may calculate a large proportion of the duct thrust, and the method of correcting inflow velocity can reduce the computational cost of coupled CFD solutions under the same working conditions. Multi-working condition optimization can effectively improve the overall efficiency of the ducted propeller.