后桨桨距角对某共轴对转螺旋桨性能影响规律研究

共轴对转螺旋桨的桨距角对前后排桨的桨间气动干扰有重要影响,能够改变螺旋桨的气动性能。为了研究后桨桨距角对共轴对转螺旋桨的气动干扰影响,改善螺旋桨的气动性能,在来流马赫数0.453 的情况下,通过调节后桨桨距角的方式对6×6 构型的共轴对转螺旋桨进行数值计算,数值计算中使用非定常雷诺平均纳维—斯托克斯（URANS）方程结合SST 湍流模型的方法,并采用T-Rex 高质量网格生成技术研究桨距角对共轴对转螺旋桨桨间气动干扰的变化规律。结果表明：后桨在前排桨产生的预旋气流作用下,能够吸收一部分前桨的切向滑流能量,且气动效率高于前桨,前后桨的气动参数在一个旋转周期内出现12 次周期性波动;共轴对转桨的前后桨转速相同时,前桨桨距角不变,减小后桨桨距角,前后桨的气动效率都会增加,后桨效率提升明显。     

Transfer learning: A new aerodynamic force identification network based on adaptive EMD and soft thresholding in hypersonic wind tunnel

The aerodynamic test in the pulse combustion wind tunnel is very important for the design, evaluation and optimization of aerodynamic characteristics of the hypersonic aircraft. The test accuracy even affects the success or failure of hypersonic aircraft development. In the aerodynamic test of pulse combustion wind tunnel, the aerodynamic signal is disturbed by the inertial force signal, which seriously affects the test accuracy of aerodynamic force. Aiming at the above problems, this paper innovatively proposes an aerodynamic intelligent identification method, that is the transfer learning network based on adaptive Empirical Modal Decomposition (EMD) and Soft Thresholding (TLN-AE&ST). Compared with the existing aerodynamic intelligent identification model based on deep learning technology, this study introduces the transfer learning idea into the aerodynamic intelligent identification model for the first time. The TLN-AE&ST effectively alleviates the problem of scarcity of training samples for intelligent models due to the high cost of wind tunnel tests, and provides a new idea for further implementation of deep learning technology in the field of wind tunnel aerodynamic testing. And this study designed residual attention block with soft threshold and dense block with adaptive EMD in TLN-AE&ST model. Residual attention block with soft threshold module can more effectively suppress the influence of instrument noise signal on model training effect. Dense block with adaptive EMD makes the deep learning model no longer a black box to a certain extent, and has certain physical significance. Finally, a series of wind tunnel tests were carried out in the Φ = 2.4 m pulse combustion wind tunnel of China Aerodynamic Research and Development Center to verify the effectiveness of TLN-AE&ST.     

Adaptive data fusion framework for modeling of non-uniform aerodynamic data

Multi-fidelity Data Fusion(MDF) frameworks have emerged as a prominent approach to producing economical but accurate surrogate models for aerodynamic data modeling by integrating data with different fidelity levels. However, most existing MDF frameworks assume a uniform data structure between sampling data sources; thus, producing an accurate solution at the required level, for cases of non-uniform data structures is challenging. To address this challenge, an Adaptive Multi-fidelity Data Fusion(...     

Downwash modelling for three-lifting-surface aircraft configuration design

This paper introduces a semi-empirical model to predict the downwash gradient at the horizontal tail of a three-lifting-surface aircraft. The superposition principle applied to well established formulations valid for two lifting surfaces is not a reasonable approach to calculate the downwash of a canard-wing-tail layout, and this paper demonstrates that such a basic technique leads to incorrect results. Therefore, an ad hoc prediction model is proposed that considers the combined nonlinear effec...     

某型联翼布局无人机的气动计算与分析

与常规布局飞机相比,联翼布局飞机具有结构重量轻、抗弯扭强度大、诱导阻力低、升力系数大和稳定性好等优点。介绍一种高效的数值模拟方法,完成对某型联翼布局无人机气动特性的初步计算与分析。基于商业软件ANSYS,整个研究过程着重于从网格建模、全机流场模拟、气动模拟数据分析三个方面,探索该型无人机纵向、横向和航向的气动特性以及主操纵面的操纵效率,实现对该型无人机稳定性和操纵性能的表征与评估。结果表明:无人机升降舵偏角的变化不影响无人机的握杆静稳定度,并且在0°~25°的升降舵偏角(下偏)范围内,升降舵偏角与升降舵的升力系数基本呈线性变化;在-4°~12°的迎角范围内,随着迎角的不断增大,该型无人机的横向静稳定性水平越大;两个垂直翼和垂尾是产生航向静稳定性的主要部件。     

Uncertainty analysis of measured geometric variations in turbine blades and impact on aerodynamic performance

Inevitable geometric variations significantly affect the performance of turbines or even that of entire engines; thus, it is necessary to determine their actual characteristics and accurately estimate their impact on performance. In this study, based on 1781 measured profiles of a typical turbine blade, the statistical characteristics of the geometric variations and the uncertainty impact are analyzed, and some commonly used uncertainty modelling methods based on PrincipalComponent Analysis(PCA)...     

低反力度跨声速转子的叶顶喷气扩稳数值研究

为进一步提高低反力度压气机的稳定工作范围，以某三级低反力度高负荷压气机首级跨声速转子为研究对象，借助三维数值模拟方法，进行了叶顶喷气扩稳研究，分析讨论了叶顶喷气提升低反力度压气机转子稳定性的机理，并探讨了不同喷气轴向位置对扩稳效果及气动性能的影响。结果表明：叶顶喷气通过削弱叶顶泄漏涡和通道激波的相互作用，抑制了转子近失速工况下泄漏涡的破碎，消除了叶顶通道的大面积堵塞，拓宽了转子的稳定工作边界；随着喷嘴的位置从叶顶前缘处沿轴向上游移动，转子的失速裕度提升量呈现出先增大后减小的趋势，综合扩稳效果和对压气机总性能参数的影响，最佳喷气轴向位置为叶顶前缘上游转子5%叶顶轴向弦长处；叶顶喷气改变了转子气动参数的径向分布，降低了转子上15%叶高范围内的负荷，同时也使得其它叶高区域的负荷提升。