共查询到18条相似文献,搜索用时 153 毫秒
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面向汽车外形空气动力学优化的代理模型方法 总被引:1,自引:0,他引:1
针对代理模型在汽车外形气动优化上的适应性研究较少的现状,运用不同数量样本点构建径向基函数(Radial Basis Function,RBF)模型、多项式模型和Kriging模型等3种常用代理模型.对比发现,在样本点相同的情况下,RBF模型的精度最高,最优解更好.在样本点增加的基础上,多项式和Kriging模型的精度提高,但计算量也大幅增加;多项式最优解更接近RBF模型的最优解,而Kriging模型最优解仍不理想.综合评估可知RBF模型更适用于汽车外气动优化. 相似文献
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研究水下自航行器(AUV) 外形及水动力性能优化的问题,为使得AUV具有较小航行阻力的同时拥有较大承载能力,需要不断进行AUV模型重建以及水动力结果分析,人工完成将会耗时很长,Isight多学科优化设计平台搭载常用的优化算法—NSGA-II遗传算法,整合Solidworks、Gambit、Fluent三大集成模块实现数据交换以进行AUV外形的建模、仿真并完成设计过程的自动化和智能的设计探索,确定最佳设计参数;仿真结果表明,最终优化后的AUV不仅减小了航行阻力并且拥有更大的承载能力;因此采用多学科优化软件Isight能够有效提高AUV外形及水动力性能优化的准确性和效率,提升其整体水动力性能。 相似文献
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《数值计算与计算机应用》2016,(4)
针对目前水下航行器和空中航行器难以以单一外形同时满足水空两种航行环境的特点,提出一种通过改变机体外形实现水空介质跨越的新型航行器.应用FLUENT对航行器的气动水动特性进行数值仿真,得到了航行器水中、空中航行的阻力、升力曲线.对结果的分析发现,通过改变外形能够满足航行器水中、空中的航行和机动要求,新型航行器的流体受弹体扰动较大,升阻特性有一定减弱,水空跨介质航行器的外形还有较大的优化空间. 相似文献
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CAEDA编译 《CAD/CAM与制造业信息化》2008,(11)
一、前言 Tosca是标准的无参数结构优化系统,可以对具有任意载荷情况的有限元模型进行拓扑和外形优化.在优化过程中,可以直接使用已经存在的有限元模型.Tosca进行结构优化的每一迭代过程均在外部求解器中进行求解,通过采用众多业界认可的标准求解器从而保证了计算结果的高质量. 相似文献
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高速列车的气动阻力与列车的外形,特别是头部外形有着密切的关系.为了改善列车气动性能降低列车运行的气动阻力,建立高速列车的三维参数化模型,以高速列车头部所受的阻力和升力为优化目标,通过FLUENT软件与Isight软件多学科优化联合仿真分析方法,利用Sculptor软件对车头部分网格自动变形,基于计算流体力学,实现对高速列车流线型头型进行减阻的多目标自动优化设计.优化完成后,得到影响优化目标阻力和升力的关键设计变量,并对优化设计变量和优化目标之间的非线性相关性进行分析.通过对比原始流线型列车气动性能发现,列车头部的长度对阻力的影响比较大,列车头部的高度能够对列车所受到的升力产生较大的影响. 相似文献
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Xiaojing Wu Weiwei Zhang Shufang Song 《Structural and Multidisciplinary Optimization》2018,57(2):639-651
Optimization techniques combined with uncertainty quantification are computationally expensive for robust aerodynamic optimization due to expensive CFD costs. Surrogate model technology can be used to improve the efficiency of robust optimization. In this paper, non-intrusive polynomial chaos method and Kriging model are used to construct a surrogate model that associate stochastic aerodynamic statistics with airfoil shapes. Then, global search algorithm is used to optimize the model to obtain optimal airfoil fast. However, optimization results always depend on the approximation accuracy of the surrogate model. Actually, it is difficult to achieve a high accuracy of the model in the whole design space. Therefore, we introduce the idea of adaptive strategy to robust aerodynamic optimization and propose an adaptive stochastic optimization framework. The surrogate model is updated adaptively by increasing training airfoils according to historical optimization results to guarantee the accuracy near the optimal design point, which can greatly reduce the number of training airfoils. The proposed method is applied to a robust aerodynamic shape optimization for drag minimization considering uncertainty of Mach number in transonic region. It can be concluded that the proposed method can obtain better optimal results more efficiently than the traditional robust optimization method and global surrogate model method. 相似文献
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A surrogate-model based multidisciplinary shape optimization method with application to a 2D subsonic airfoil 总被引:1,自引:0,他引:1
A surrogate-model based shape optimization method is presented and applied to the case of the multidisciplinary shape optimization of a 2D NACA subsonic airfoil. The cost function is designed so that both the far-field radiated noise and the aerodynamic forces are controlled. The surrogate model is based on the Kriging optimal interpolation technique. In order to increase the efficiency of the method, a dynamic Kriging method is developed, which can be interpreted as an Adaptive Mesh Refinement method in the shape optimization parameters. 相似文献
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以英国汽车工业研究协会(Motor Industry Research Association,MIRA)阶背模型为基本模型,用参数化建模方法建立其纵向对称面的二维模型.运用优化拉丁超立方方法对每组参数化方案生成600组样本点;将MATLAB与Gambit结合,自动快速生成其网格模型;用FLUENT计算每个样本点的气动阻力.建立径向基神经网络(Radial Basis Function Neural Network,RBFNN)近似模型,以阻力最小为优化目标,采用多岛遗传算法优化外形参数;对优化后的结果进行数值模拟,结果表明阻力减少31.9%.三维验证结果表明:二维优化结果不能完全代表三维结果,直接进行三维优化设计的效果更好. 相似文献
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Nicolas Rosset Guillaume Cordonnier Regis Duvigneau Adrien Bousseau 《Computer Graphics Forum》2023,42(2):427-437
The design of car shapes requires a delicate balance between aesthetic and performance. While fluid simulation provides the means to evaluate the aerodynamic performance of a given shape, its computational cost hinders its usage during the early explorative phases of design, when aesthetic is decided upon. We present an interactive system to assist designers in creating aerodynamic car profiles. Our system relies on a neural surrogate model to predict fluid flow around car shapes, providing fluid visualization and shape optimization feedback to designers as soon as they sketch a car profile. Compared to prior work that focused on time-averaged fluid flows, we describe how to train our model on instantaneous, synchronized observations extracted from multiple pre-computed simulations, such that we can visualize and optimize for dynamic flow features, such as vortices. Furthermore, we architectured our model to support gradient-based shape optimization within a learned latent space of car profiles. In addition to regularizing the optimization process, this latent space and an associated encoder-decoder allows us to input and output car profiles in a bitmap form, without any explicit parameterization of the car boundary. Finally, we designed our model to support pointwise queries of fluid properties around car shapes, allowing us to adapt computational cost to application needs. As an illustration, we only query our model along streamlines for flow visualization, we query it in the vicinity of the car for drag optimization, and we query it behind the car for vortex attenuation. 相似文献
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基于NURBS方法的气动外形优化设计 总被引:1,自引:0,他引:1
采用NURBS曲线曲面,对钝锥弹头和钝双锥弹体建立参数化曲面模型,取NURBS曲线控制点作为设计参数,应用高超声速面元法求解气动力特性,在给定设计约束下,采用遗传算法进行气动外形优化设计,并对优化结果进行了比较分析。结果表明,采用NURBS方法构造参数化外形,并结合优化技术可方便快速地获得所需最优外形;与应用二次曲线构造参数化外形相比,该方法对弹体形状控制更加灵活,并可局部修改弹头曲线形状。因此,基于NURBS方法发展整套的系统优化设计算法很有现实意义和应用价值。 相似文献
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Variable-fidelity expected improvement method for efficient global optimization of expensive functions 总被引:1,自引:0,他引:1
Yu Zhang Zhong-Hua Han Ke-Shi Zhang 《Structural and Multidisciplinary Optimization》2018,58(4):1431-1451
The efficient global optimization method (EGO) based on kriging surrogate model and expected improvement (EI) has received much attention for optimization of high-fidelity, expensive functions. However, when the standard EI method is directly applied to a variable-fidelity optimization (VFO) introducing assistance from cheap, low-fidelity functions via hierarchical kriging (HK) or cokriging, only high-fidelity samples can be chosen to update the variable-fidelity surrogate model. The theory of infilling low-fidelity samples towards the improvement of high-fidelity function is still a blank area. This article proposes a variable-fidelity EI (VF-EI) method that can adaptively select new samples of both low and high fidelity. Based on the theory of HK model, the EI of the high-fidelity function associated with adding low- and high-fidelity sample points are analytically derived, and the resulting VF-EI is a function of both the design variables x and the fidelity level l. Through maximizing the VF-EI, both the sample location and fidelity level of next numerical evaluation are determined, which in turn drives the optimization converging to the global optimum of high-fidelity function. The proposed VF-EI is verified by six analytical test cases and demonstrated by two engineering problems, including aerodynamic shape optimizations of RAE 2822 airfoil and ONERA M6 wing. The results show that it can remarkably improve the optimization efficiency and compares favorably to the existing methods. 相似文献
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Efficient aerodynamic shape optimization of transonic wings using a parallel infilling strategy and surrogate models 总被引:7,自引:0,他引:7
J. Liu W.-P. Song Z.-H. Han Y. Zhang 《Structural and Multidisciplinary Optimization》2017,55(3):925-943
Surrogate models are used to dramatically improve the design efficiency of numerical aerodynamic shape optimization, where high-fidelity, expensive computational fluid dynamics (CFD) is often employed. Traditionally, in adaptation, only one single sample point is chosen to update the surrogate model during each updating cycle, after the initial surrogate model is built. To enable the selection of multiple new samples at each updating cycle, a few parallel infilling strategies have been developed in recent years, in order to reduce the optimization wall clock time. In this article, an alternative parallel infilling strategy for surrogate-based constrained optimization is presented and demonstrated by the aerodynamic shape optimization of transonic wings. Different from existing methods in which multiple sample points are chosen by a single infill criterion, this article uses a combination of multiple infill criteria, with each criterion choosing a different sample point. Constrained drag minimizations of the ONERA-M6 and DLR-F4 wings are exercised to demonstrate the proposed method, including low-dimensional (6 design variables) and higher-dimensional problems (up to 48 design variables). The results show that, for surrogate-based optimization of transonic wings, the proposed method is more effective than the existing parallel infilling strategies, when the number of initial sample points are in the range from N v to 8N v (N v here denotes the number of design variables). Each case is repeated 50 times to eliminate the effect of randomness in our results. 相似文献