涡桨飞机螺旋桨滑流气动干扰效应及流动机理

螺旋桨滑流对飞机各气动部件的干扰是涡桨飞机气动设计中面临的难点之一。以某双发涡桨支线客机为对象，采用数值模拟手段分析了滑流对机翼、平尾、垂尾的影响及其流动机理。计算采用基于动态面搭接网格技术的非定常方法，气动力与表面压力分布的计算结果均与实验值吻合良好。研究结果表明：在滑流影响下，全机升力和阻力有所增加，升阻比和纵向静稳定度有所降低，并在无侧滑状态下产生了滚转力矩和偏航力矩；在不同展向位置，滑流对机翼表面流动分离的影响存在显著的差异。在螺旋桨下行运动一侧，滑流的旋转减小了当地迎角，同时桨后气流速度较高，翼面流动分离被有效抑制。在螺旋桨上行运动一侧，滑流的旋转增大了当地迎角，而且桨后气流速度较低，因而翼面流动分离并未得到明显改善；在中小迎角下，滑流对背景飞机平尾当地的动压没有产生影响，但增加了下洗角变化率，进而导致平尾效率降低；垂尾的侧力与偏航力矩是由滑流的侧洗引起的，而滑流的侧洗又与左右两侧机翼升力分布的不对称性有关。

Interference effects and flow mechanism of propeller slipstream for turboprop aircraft

The interference of the propeller slipstream on the aircraft components is one of the difficult points in aerodynamic design of turboprops. In the present study, the influence of propeller slipstream on wing, horizontal tail and vertical tail and its flow mechanism for a twin-engine turboprop regional airliner are investigated through numerical simulations. The computations are performed via the unsteady numerical method based on the dynamic patched grid. The calculated aerodynamic forces and surface pressure distributions agree well with the experimental data. The results indicate that under the influence of slipstream, the lift and drag of the whole plane have increased while the lift-drag ratio and the longitudinal static stability are reduced. What's more, the plane even suffers rolling and yawing moment in the non-sideslip condition. There are significant differences in the effect of slipstream on the separation of wing surfaces at different spanwise positions. On the downward side of the propeller, the flow separation is effectively suppressed because of the decreases in the local angle of attack caused by the swirl of the slipstream and a strong flow acceleration. However, on the upward side of the propeller, there is no significant improvement of the flow separation due to an increase in the local angle of attack and a slow flow speed. The slipstream has no effect on local dynamic pressure around the horizontal tail of the reference aircraft at low and moderate angles of attack, but it increases the downwash gradient, resulting in the reduction of the tail efficiency. The side force and the yawing moment of the vertical tail are caused by the sidewash of the slipstream which is closely related to the asymmetric wing-lift distribution.