风扇转速对混合动力飞翼布局进排气-风扇流场的影响研究

Effects of fan speed on the integrated intake-fan-nozzle flow field of a hybrid flying-wing aircraft

  • 摘要: 使用电驱螺旋桨/风扇作为推进装置的混合动力飞行器具有低污染、低热信号、低噪声等优势,是航空领域未来发展的重要方向。为探究混合动力飞翼布局飞行器进排气-风扇流场情况,本文基于多重参考坐标系(multiple reference frame, MRF)准定常数值模拟方法、剪切应力输运SST k-ω两方程湍流模型以及静止域与旋转域面交界的结构网格,搭建了“内埋式进气道-电驱风扇-喷管”构型的流场仿真模型,研究了转速对进排气-风扇流场的影响和流动机理。研究表明,旋转风扇的加入一定程度上可以改善进气道的进气均匀度,降低进气道出口截面压力畸变系数,转速6000 r/min较无风扇时压力畸变指数减小59.7%;随着转速增加,总压恢复系数变化不明显,压力畸变指数先减小后增大;叶尖间隙流的流动分离受叶尖马赫数增加而逐渐加剧,并对中心区域流动造成扰动,进而一定程度上影响喷管的流动分布;喷管内气流速度沿轴向逐渐升高,沿径向先升高后降低。

     

    Abstract: Hybrid-powered aircraft that use electric-driven propellers/fans as propulsion devices have advantages such as low pollution, low thermal signals, and low noise, and are an important direction for the future development of the aviation field. To investigate the intake-fan-nozzle flow field of a hybrid-powered flying-wing layout aircraft, this paper establishes a flow field simulation model of the "in-molded intake-electric-driven fan-nozzle" configuration based on the Multiple Reference Frame (MRF) quasi-steady numerical approach, the Shear Stress Transport (SST) k-ω two-equation turbulence model, and the structured grid at the interface between the stationary domain and the rotating domain. The study explores the influence of rotation speed on the intake-fan-nozzle flow field and the underlying flow mechanism by using the fan speed as the research variable. The results show that the addition of the rotating fan can, to some extent, improve the uniformity of air intake in the intake duct, reduce the pressure distortion coefficient at the outlet section of the intake duct, and that the pressure distortion index decreases by 59.7% compared to the case without a fan at 6000 r/min; as the rotational speed increases, the total pressure recovery coefficient changes only slightly, and the pressure distortion index first decreases and then increases. The flow separation of the tip gap flow is gradually intensified with the increase of the tip Mach number, and can disturb the flow in the central area, thereby affecting the flow distribution at the nozzle to a certain extent. The airflow velocity in the nozzle gradually increases along the axial direction as the cross-sectional area decreases; along the radial direction, it first increases and then decreases due to the influence of the flow separation between the tip gap and the central body wall surface.

     

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