检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

飞翼布局高低速一体化气动优化设计

航空学报 2024年第15期45卷 187-205页

作者：赵轲邓俊黄江涛陈树生高正红西北工业大学航空学院西安710072 飞行器基础布局全国重点实验室西安710072 中国空气动力研究与发展中心空天技术研究所绵阳621000

飞翼布局由于在气动、隐身和结构等方面的综合优势,是未来最有潜力的飞行器气动布局形式。关于飞翼布局的气动设计研究,学术界开展了大量的设计分析,研究发现低速起降性能和操控是飞翼布局性能和安全的主要难点。对于飞翼布局无人机和... 详细信息

飞翼布局由于在气动、隐身和结构等方面的综合优势,是未来最有潜力的飞行器气动布局形式。关于飞翼布局的气动设计研究,学术界开展了大量的设计分析,研究发现低速起降性能和操控是飞翼布局性能和安全的主要难点。对于飞翼布局无人机和作战飞机,由于隐身设计的影响,使得其低速起降性能、操控特性更加严苛,以往的研究主要集中在高速巡航的设计,关于低速设计研究很少,因此基于高性能离散伴随优化设计平台,开展了某飞翼布局无人机的高低速综合设计研究,分析对比了不同低速设计模型对飞机低速特性的影响,在此基础上,建立了高低综合设计模型,全面提升了飞机的高低速性能,经过对结果的分析,总结了高低速一体化设计的要点和规律,为飞翼布局的气动设计提供了有力的设计模型和参考。

关键词：飞翼布局离散伴随气动优化低速设计流动分离

在线全文

学校读者我要写书评

暂无评论

两级入轨航天器级间分离姿态精确控制

航空学报 2024年第13期45卷 266-280页

作者：姜权峰陈树生杨华李祚泰高正红西北工业大学航空学院西安710072 飞行器基础布局全国重点实验室西安710072

两级入轨航天器(TSTO)级间分离过程中对轨道级、助推级的姿态精确控制尤为重要。数值模拟可以较为准确地预测级间分离这种飞行器多体分离问题,运用非结构嵌套网格技术及双时间步法耦合流动控制方程、刚体运动方程求解TSTO在攻角-2°、... 详细信息

两级入轨航天器(TSTO)级间分离过程中对轨道级、助推级的姿态精确控制尤为重要。数值模拟可以较为准确地预测级间分离这种飞行器多体分离问题,运用非结构嵌套网格技术及双时间步法耦合流动控制方程、刚体运动方程求解TSTO在攻角-2°、马赫数6、海拔高度30 km的级间分离过程,发展了一种优化轨道级、助推级在级间分离过程的运动姿态的技术。该技术通过松弛迭代法提取轨道级、助推级的无舵偏气动力数据,基于无舵偏气动力数据设计气动舵面、燃气舵所需要提供的俯仰力矩,使得轨道级、助推级的运动姿态更加接近设计目标。数值模拟结果表明,TSTO在分离过程中两级之间会存在强烈的气动干扰,严重影响两级的姿态控制,发展的技术可为TSTO分离过程中轨道级、助推级的舵面运动、燃气舵工作状态设计提供参考,提高TSTO级间分离的效率、安全性。

关键词：两级入轨多体分离高超声速嵌套网格松弛因子法

基于全局/梯度优化方法的宽速域乘波-机翼布局气动设计

在线全文

学校读者我要写书评

暂无评论

航空学报 2024年第6期45卷 134-148页

作者：陈树生冯聪张兆康赵轲张新洋高正红西北工业大学航空学院西安710072

宽速域高超声速飞行器是航空航天领域新的战略制高点,其飞行速域与空域极大化特点导致亚/跨/超/高超声速气动性能难以兼顾。为了缓解高低速气动设计的矛盾,以典型宽速域乘波-机翼布局为研究对象,结合基于代理模型的全局优化方法和基于... 详细信息

宽速域高超声速飞行器是航空航天领域新的战略制高点,其飞行速域与空域极大化特点导致亚/跨/超/高超声速气动性能难以兼顾。为了缓解高低速气动设计的矛盾,以典型宽速域乘波-机翼布局为研究对象,结合基于代理模型的全局优化方法和基于伴随梯度的局部优化方法,对该宽速域构型的布局参数和剖面形状进行了从全局到局部的多目标分步优化。结果表明,在约束亚声速升力系数、高超声速阻力系数的情况下,基于代理模型的布局参数优化方法能够在维持高超声速气动性能的同时,将亚声速的升阻比提升9.5%。进一步选取布局参数优化结果 Pareto面上亚声速气动特性最优的构型,利用基于伴随梯度的优化方法,对机翼剖面进行梯度优化。优化结果表明,梯度优化能够有效地改善飞行器亚/高超声速状态下的阻力特性,并将翼型在几何上优化为兼顾亚/高超声速气动特性的双S翼型。通过上述从布局参数到剖面参数的优化,乘波-机翼构型的亚声速升阻比相比初始构型提升了12.4%,高超声速升阻比相比原始构型提升了6.2%。

关键词：乘波-机翼构型宽速域代理模型伴随方法分步优化

变体飞行器变形方式及气动布局设计关键技术研究进展

在线全文

学校读者我要写书评

暂无评论

航空学报 2024年第6期45卷 1-47,F0002页

作者：陈树生贾苜梁刘衍旭高正红向星皓西北工业大学航空学院西安710072 中国空气动力研究与发展中心绵阳621000

能够根据任务需求、飞行环境自适应改变外形来达到最佳飞行性能的变体飞行器已成为未来飞行器发展的重要方向之一。综述了变体飞行器变形方式及气动布局设计关键技术研究现状。首先,按照时间发展历程,将变体技术的发展分为简单机械变形... 详细信息

能够根据任务需求、飞行环境自适应改变外形来达到最佳飞行性能的变体飞行器已成为未来飞行器发展的重要方向之一。综述了变体飞行器变形方式及气动布局设计关键技术研究现状。首先,按照时间发展历程,将变体技术的发展分为简单机械变形、多维度柔性变形2个阶段。其次,按照变体部位和变形方式详细介绍了头部变体、机翼变体、动力装置变体和组合变体方案的发展历程和现状,重点阐述了可变后掠机翼、可变前掠机翼、折叠机翼、伸缩机翼、斜置机翼、连续变弯度机翼等机翼变体方案的研究进展,总结其在不同布局构型上的应用,并分析了各自的气动、操稳特性。之后,归纳了飞行器变体的实现目的,将其分为单域最优变构型、多域融合变构型、一器多能变构型3种。接着,与固定外形飞行器进行对比,梳理了变体飞行器因为变构型的实现而衍生的气动布局与总体协调设计、时变空气动力学效应评估、气动布局方案优化、多学科耦合设计等方面的关键技术难点,重点对变体飞行器动态气动力计算方法和气动优化设计技术的研究进展和现状进行了综述和分析。最后,展望了变体技术未来研究方向和发展前景,面向宽速域和大空域飞行需求,探索可以提高多飞行任务性能的新概念变形方式,建立智能变体设计模型及多学科强耦合一体化设计体系将成为重要发展趋势。

关键词：变体飞行器变形方式机翼变体优化设计非定常效应多学科一体化

A low-diffusion robust flux splitting scheme towards wide-ranging Mach number flows

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2021年第5期34卷 628-641页

作者： shusheng chen Fangjie CAI Xinghao XIANG Zhenghong GAO Chao YAN School of Aeronautics Northwestern Poly technical UniversityXi'an 710072China AVIC The First Aircraft Institute Xi'an 710089China China Academy of Launch Vehicle Technology Beijing 100076China State Key Laboratory of Aerodynamics China Aerodynamics Research and Development CenterMianyang 621000China School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China

This paper develops a low-diffusion robust flux splitting scheme termed TVAP to achieve the simulation of wide-ranging Mach number *** on Toro-Vazquez splitting approach,the new scheme splits inviscid flux into convective system and pressure *** method introduces Mach number splitting function and numerical sound speed to evaluate advection ***,pressure diffusion term,pressure momentum flux,interface pressure and interface velocity are constructed to measure pressure ***,typical test problems are utilized to systematically assess the robustness and accuracy of the resulting *** stability analysis and a series of numerical cases,such as double shear-layer problem and hypersonic viscous flow over blunt cone,demonstrate that TVAP scheme achieves excellent low diffusion,shock stability,contact discontinuity and low-speed resolution,and is potentially a good candidate for wide-ranging Mach number flows.

关键词： Computational Fluid Dynamics(CFD) Flux splitting Accuracy Robustness Wide-ranging Mach number

Bayesian uncertainty analysis of SA turbulence model for supersonic jet interaction simulations

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2022年第4期35卷 185-201页

作者： Jinping LI shusheng chen Fangjie CAI Sheng WANG Chao YAN School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China AVIC The First Aircraft Institute Xi'an 710089China China Academy of Launch Vehicle Technology Beijing 100076China

The Reynolds Averaged Navier-Stokes(RANS) models are still the workhorse in current engineering applications due to its high efficiency and robustness. However, the closure coefficients of RANS turbulence models are determined by model builders according to some simple fundamental flows, and the suggested values may not be applicable to complex flows, especially supersonic jet interaction flow. In this work, the Bayesian method is employed to recalibrate the closure coefficients of Spalart-Allmaras(SA) turbulence model to improve its performance in supersonic jet interaction problem and quantify the uncertainty of wall pressure and separation length. The embedded model error approach is applied to the Bayesian uncertainty analysis. Firstly, the total Sobol index is calculated by non-intrusive polynomial chaos method to represent the sensitivity of wall pressure and separation length to model parameters. Then, the pressure data and the separation length are respectively served as calibration data to get the posterior uncertainty of model parameters and Quantities of Interests(Qo Is). The results show that the relative error of the wall pressure predicted by the SA turbulence model can be reduced from 14.99% to 2.95% through effective Bayesian parameter estimation. Besides, the calibration effects of four likelihood functions are systematically evaluated. The posterior uncertainties of wall pressure and separation length estimated by different likelihood functions are significantly discrepant, and the Maximum a Posteriori(MAP) values of parameters inferred by all functions show better performance than the nominal values. Finally, the closure coefficients are also estimated at different jet total pressures. The similar posterior distributions of model parameters are obtained in different cases, and the MAP values of parameters calibrated in one case are also applicable to other cases.

关键词： Bayesian calibration MAP estimation SA turbulence model Supersonic jet interaction Uncertainty quantification

Deep learning for inverse design of low-boom supersonic configurations

在线全文

学校读者我要写书评

暂无评论

Advances in Aerodynamics 2023年第1期5卷 247-266页

作者： shusheng chen Jiyan Qiu Hua Yang Wu Yuan Zhenghong Gao School of Aeronautics Northwestern Polytechnical UniversityXi’an 710072China AVIC The First Aircraft Institute Xi’an 710089China Computer Network Information Center Chinese Academy of SciencesBeijing 100190China

Mitigating the sonic boom to an acceptable stage is crucial for the next generation of supersonic *** primary way to suppress sonic booms is to develop a low sonic boom aerodynamic shape *** paper proposes an inverse design approach to optimize the near-field signature of an aircraft,making it close to the shaped ideal ground signature after propagation in the *** introducing the Deep Neural Network(DNN)model for the first time,a predicted input of Augmented Burgers equation is inversely *** the K-fold cross-validation method,the pre-dicted ground signature closest to the target ground signature is ***,the corresponding equivalent area distribution is calculated using the classical Whitham’s F-function theory from the optimal near-field *** inversion method is vali-dated using the classic example of the C608 vehicle provided by the Third Sonic Boom Prediction Workshop(SBPW-3).The results show that the design ground signature is consistent with the target *** equivalent area distribution of the design result is smoother than the baseline distribution,and it shrinks significantly in the rear ***,the robustness of this method is verified through the inverse design of sonic boom for the non-physical ground signature target.

关键词： Low boom configuration Deep neural network Augmented Burgers equation Supersonic transports Equivalent area

Highly transparent and super-wettable nanocoatings hybridized with isocyanate-silane modified surfactant for multifunctional applications

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Nano Materials Science 2022年第2期4卷 151-168页

作者： Man Kwan Law Ying Zhao Weibin Zhang Rui Wang Mingcheng Shi Yunxiao Zhang shusheng chen Jinglei Yang Department of Mechanical and Aerospace Engineering The Hong Kong University of Science and TechnologyClear Water BayHong Kong SARChina

Highly transparent and super-wettable nanocoatings for multifunctional applications with outstanding physical properties are in high ***,such nanocoatings resistant to water invasion and Ultraviolet(UV)weathering remain a significant *** this work,physically durable coatings based on inorganic nanoparticles(NPs)and an organic segment(isocyanate-silane modified surfactant)have been synthesized via a sol-gel *** is noteworthy the isocyanate-silane with-NH-C=O-functional group creates a strong bonding between the highly hydrophilic surfactant and the inorganic *** in-house synthesized organic segment can render the coating long-lasting wetting properties and resist to be washed away by water,while the inorganic NPs can form sturdy covalent bonds with the nano-scale hierarchical structure on the glazing substrate to improve the *** nanocoating demonstrates high transparency with superwetting property(water contact angle,WCA=4.4±0.3°),effective de-frosting *** invasion or UV accelerated weathering tests do not significantly affect the self-cleaning performance of *** properties,including coating adhesion,hardness,Young's modulus,and abrasion resistance are systematically ***,this clear coating shows prominent infrared shielding property attributed to Antimony-doped tin oxide(Sb-doped SnO_(2))*** developed nanocoating process is easy to scale up for larger areas that require multipurpose self-cleaning functions.

关键词： Nanocoating Sol-gel approach Multifunctionality High transparency Superwetting Durability

在线全文

学校读者我要写书评

暂无评论

高等教育品牌经营的战略选择

教育发展研究 2005年第11期25卷 34-37页

作者：佘正松陈树生西华师范大学

自1999年高校扩大招生以来,目前全国各类高等学校在校生已超过2000万人,高等教育毛入学率超过19%,我国高等教育实现了一次历史性大跨越,创造了世界高等教育史上的奇迹.然而,任何一次大跨越都必须打破原来的平衡,扩招之后,如何保证教学质... 详细信息

自1999年高校扩大招生以来,目前全国各类高等学校在校生已超过2000万人,高等教育毛入学率超过19%,我国高等教育实现了一次历史性大跨越,创造了世界高等教育史上的奇迹.然而,任何一次大跨越都必须打破原来的平衡,扩招之后,如何保证教学质量,如何提高管理水平已经成为我国高等教育面临一个很重要的问题.

关键词：高等教育毛入学率品牌经营市场经济地位高等教育史发展中国家扩大招生高等学校教学质量世贸组织