排序方式: 共有27条查询结果,搜索用时 15 毫秒
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全流道的进气道/风扇一体化计算虽然能捕捉到全面、完整的流场细节,但仍然需要消耗大量的计算资源。为了节约计算成本,利用有限的设备达到快速高精度计算的目的,采用自行发展的块体积力模型替代真实叶片进行一体化计算。该模型将叶片流域沿周向等距分成若干块,每个块的体积力源项关联于叶片前缘参数。研究结果表明:该体积力模型能够准确地模拟出流场特征与细节。在均匀来流下,各参数的相对误差在0.5%以内。同时,在大S弯进气道高畸变来流条件下,与冻结转子方法计算结果相比,总压比、总温比和等熵效率的相对误差分别为4.49%,0.26%和2.38%。 相似文献
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This paper discusses a physics-informed methodology aimed at reconstructing efficiently the fluid state of a system. Herein, the generation of an accurate reduced order model of two-dimensional unsteady flows from data leverages on sparsity-promoting statistical learning techniques. The cornerstone of the approach is l1 regularised regression, resulting in sparsely-connected models where only the important quadratic interactions between modes are retained. The original dynamical behaviour is reproduced at low computational costs, as few quadratic interactions need to be evaluated. The approach has two key features. First, interactions are selected systematically as a solution of a convex optimisation problem and no a priori assumptions on the physics of the flow are required. Second, the presence of a regularisation term improves the predictive performance of the original model, generally affected by noise and poor data quality. Test cases are for two-dimensional lid-driven cavity flows, at three values of the Reynolds number for which the motion is chaotic and energy interactions are scattered across the spectrum. It is found that: (A) the sparsification generates models maintaining the original accuracy level but with a lower number of active coefficients; this becomes more pronounced for increasing Reynolds numbers suggesting that extension of these techniques to real-life flow configurations is possible; (B) sparse models maintain a good temporal stability for predictions. The methodology is ready for more complex applications without modifications of the underlying theory, and the integration into a cyber-physical model is feasible. 相似文献
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针对航空发动机涡轮叶片气膜冷却孔加工问题,选取GH4037合金为研究对象,利用德国德玛吉精密激光打孔机床进行毫秒激光倾斜打孔试验,并采用COMSOL软件进行仿真。在倾角为15°的情况下,测试了激光光束离焦量分别为负离焦、零离焦和正离焦情况下的打孔质量,在零离焦打孔时,不仅打孔深度较大,且在入口处的圆度较好,横纵向孔径差值最小。在30°和45°2种倾角下进行打孔试验对比,结果表明:在零离焦情况下,激光脉冲数为180、重复频率为60 Hz、脉宽为1 ms、脉冲能量为1.2~1.8 J,且在无辅助气体的斜孔加工条件下,倾斜角度为30°时的孔形形貌较好,倾斜角度为45°时的孔形形貌较差,主要原因在于倾斜角度增大,靶材反射率提高,靶材表面的光斑面积增加,孔口处的燃烧效应增强,产生明显的二次烧蚀现象。采用COMSOL软件的固体传热和变形几何模块对打孔过程进行仿真,仿真结果可在一定程度上预测试验结果。 相似文献
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J. Gorosabel A. de Ugarte Postigo A.J. Castro-Tirado I. Agudo M. Jelínek S. Leon T. Augusteijn J.P.U. Fynbo M.J. Michałowski D. Xu P. Ferrero D.A. Kann A. LLorente M. Bremer J.-M. Winters C.C. Thöne J. Cepa 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2011
We present the preliminary results of the recent Hα narrow-band imaging carried out for NGC 2770 with the Gran Telescopio Canarias (GTC) equipped with OSIRIS. We put the polarization measurements reported in Gorosabel et al. (2010) for SN 2007uy and SN 2008D in the context of the morphological information inferred from the Hα imaging. We estimated the orientation of the interstellar polarization (ISP) at the position of SN 2007uy and, most interestingly, at the site of SN 2008D which has been subject of an intensive debate due to its possible connection with Gamma-Ray Bursts (GRBs). The Hα imaging reveals a clumpy interstellar medium (ISM) composed of hundreds of compact emitting regions, for which we determined their sizes. The derived size for the Hα emitting region coincident with SN 2008D is consistent with the ISM cell size limits imposed by Gorosabel et al. (2010) based on millimetric data. A deeper data analysis is under way and will be published elsewhere. This article represents the first attempt to study the site of a possible GRB-like event combining millimetric, polarimetric and narrow-band data. 相似文献
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Andrea DA RONCH Antonino VENTURA Marcello RIGHI Matteo FRANCIOLINI Marco BERCI Daniel KHARLAMOV 《中国航空学报》2018,31(4):617-631
Analytical indicial aerodynamic functions are calculated for several trapezoidal wings in subsonic flow, with a Mach number 0.3 Ma 0.7. The formulation herein proposed extends wellknown aerodynamic theories, which are limited to thin aerofoils in incompressible flow, to generic trapezoidal wing planforms. Firstly, a thorough study is executed to assess the accuracy and limitation of analytical predictions, using unsteady results from two state-of-the-art computational fluid dynamics solvers as cross-validated benchmarks. Indicial functions are calculated for a step change in the angle of attack and for a sharp-edge gust, each for four wing configurations and three Mach numbers. Then, analytical and computational indicial responses are used to predict dynamic derivatives and the maximum lift coefficient following an encounter with a one-minus-cosine gust. It is found that the analytical results are in excellent agreement with the computational results for all test cases. In particular, the deviation of the analytical results from the computational results is within the scatter or uncertainty in the data arising from using two computational fluid dynamics solvers. This indicates the usefulness of the developed analytical theories. 相似文献
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钝头体窄条翼布局导弹在大攻角下拥有极为优异的纵向气动特性,但横向容易失稳,做快速机动时容易诱发非指令的横向不稳定运动。通过开展高速风洞自由摇滚试验和数值模拟,研究了窄条翼导弹自由摇滚特性和流动机理,试验与计算吻合较好。研究发现:较大迎角时,窄条翼面积中心距离尾舵前缘根部5~6倍直径时,模型会进入极限环摇滚,窄条翼位置对模型稳定性有显著的影响,去掉窄条翼或尾舵时,模型均不会进入摇滚;模型空间流场特性表明,气流经过窄条翼时形成的片涡,对背风舵产生强烈的干扰,抑制了尾舵涡的形成和发展,使背风舵动态失稳,导致模型进入极限环摇滚。 相似文献