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501.
《中国航空学报》2023,36(2):201-212
Distributed Electric Propulsion (DEP) aircraft use multiple electric motors to drive the propulsors, which gives potential benefits to aerodynamic-propulsion interaction. To investigate and quantify the aerodynamic-propulsion interaction effect of the wing section, we built a DEP demonstrator with 24 “high-lift” Electric Ducted Fans (EDFs) distributed along the wing’s trailing edge. This paper explores and compares the aero-propulsion coupling characteristics under various upstream speed, throttle, and EDF mounting surface deflection angles using a series of wind tunnel tests. We compare various lift-augmentation power conditions to the clean configuration without propulsion unit under the experiment condition of 15–25 m/s freestream flow and angles of attack from ?4° to 16°. The comparison of computational results to the experimental results verifies the effectiveness of the computational fluid dynamic analysis method and the modeling method for the DEP configuration. The results show that the EDFs can produce significant lift increment and drag reduction simultaneously, which is accordant with the potential benefit of Boundary Layer Ingestion (BLI) at low airspeed. 相似文献
502.
《中国航空学报》2023,36(3):80-95
A direct numerical simulation of hypersonic Shock wave and Turbulent Boundary Layer Interaction(STBLI) at Mach 6.0 on a sharp 7° half-angle circular cone/flare configuration at zero angle of attack is performed. The flare angle is 34° and the momentum thickness Reynolds number based on the incoming turbulent boundary layer on the sharp circular cone is Reθ = 2506. It is found that the mean flow is separated and the separation bubble occurring near the corner exhibits unsteadiness. The Reynolds analogy factor changes dramatically across the interaction, and varies between 1.06 and 1.27 in the downstream region, while the QP85 scaling factor has a nearly constant value of 0.5 across the interaction. The evolution of the reattached boundary layer is characterized in terms of the mean profiles, the Reynolds stress components, the anisotropy tensor and the turbulence kinetic energy. It is argued that the recovery is incomplete and the near-wall asymptotic behavior does not occur for the hypersonic interaction. In addition, mean skin friction decomposition in an axisymmetric turbulent boundary layer is carried out for the first time. Downstream of the interaction, the contributions of transverse curvature and body divergence are negligible, whereas the positive contribution associated with the turbulence kinetic energy production and the negative spatial-growth contribution are dominant. Based on scale decomposition, the positive contribution is further divided into terms with different spanwise length scales. The negative contribution is analyzed by comparing the convective term, the streamwise-heterogeneity term and the pressure gradient term. 相似文献
503.
Ultrasonic vibration-assisted technology is widely utilized in the performance research and manufacturing process of metallic materials owing to its advantages of introducing highfrequency acoustic systems. However, the acoustic plasticity constitutive model and potential mechanism, involving Ti3Al intermetallic compounds, have not yet been clarified. Therefore, the Ultrasonic-K-M hybrid acoustic constitutive model of Ti3Al was established by considering the stress superpos... 相似文献
504.
《中国航空学报》2023,36(8):24-31
Mach number effects on the near-wall turbulence in the absence of outer motions remain unclear so far. The present study extends the Minimal Flow Units (MFUs), a widely applied method to investigate near-wall turbulence free from the impact of large-scale motions in the outer region in incompressible channel flows, to compressible wall-bounded turbulence. The compressible near-wall turbulence in MFU proves accurate in replicating near-wall statistics, independent of Mach number and statistically equivalent to the universal signals extracted from the full-sized channel. It is further utilized as universal signals in the predictive models of compressible near-wall turbulence, which is capable of accurately predicting variances and joint probability density functions of velocity and temperature fluctuations. 相似文献
505.
无线无源传感技术作为适应恶劣工作环境的重要手段,在飞行器防热层烧损监测应用中仍然面临无源信息无法跨越金属机体的困难。提出一种基于声学能量耦合与电路熔断相结合的防热层烧损无源监测新方法。阐述了该方法的原理、实现方案,并对跨越金属介质获得防热层内埋熔丝状态信息的关键原理进行了实验验证,结果表明该方法能有效穿透典型厚度铝合金舱壁,在25 ℃–85 ℃的温度范围内均可有效辨识检测信号的变化,并且能有效避免强震动环境影响。方法避免了对金属机体结构件的开孔和破坏,可用于对高速飞行器、再入航天器和新一代空天往返运输系统防热层的在线健康监测。 相似文献
506.
射流-横向流相互干涉下旋涡的形成与衰减 总被引:2,自引:0,他引:2
射流-横向流干涉流场中存在三种不同的涡运动:附着涡,尾迹涡和剪切涡。本文利用荧光丝和七孔探针作为流场观测手段,研究了干涉流场中涡的形成机理及其相互干扰。此外,文中还分析讨论了影响流向涡的发展和衰减的主要因素。 相似文献
507.
508.
509.
二维旋转湍流边界层内气固两相流动的数值模拟 总被引:1,自引:0,他引:1
本文用修正的DOROD-FEM方法对不可压流体二维旋转湍流边界层进行了数值模拟,得到了与实验数据较符合的边界层形状因子和壁面摩擦系数的计算结果。采用单向耦合(One-way Coupling)方法,计算了固粒在湍流边界层和无粘流中的运动轨迹,给出了壁面被固粒撞击后的冲蚀磨损分布,分析了近壁流场性态与壁面冲蚀磨损的关系。 相似文献
510.