共查询到18条相似文献,搜索用时 125 毫秒
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本文结合高精度TVD格式的数值通量和时间进展多步法给出了一种求解定常流问题的数值方法。同时给出一些特殊处理来加快数值解的收敛速度。本文用以上方法计算了翼型跨音速绕流问题,结果表明此方法具有分辨率高,收敛速度较快之性质。 相似文献
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紊流跨声速绕流的数值模拟 总被引:3,自引:0,他引:3
本文采用Baldwin-Lomax代数紊流模型,利用LU-ADI方法数值模拟了跨声速范围内紊流绕二元翼型的流动特性。通过数值实验证明本文所使用的方法求解跨声速绕流问题是成功的,它能给出同实验吻合较好的数值解。 相似文献
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翼型气动优化设计的核心在于快速、准确的流动性能分析与快速、可靠的寻优算法。本文提出通过控制翼型表面预期流动分布,应用气动反问题方法,求解性能优化的翼型气动设计新方法。本文的翼型流动分析是基于位势流动与边界层积分方程的迭代解法。气动参数寻优采用了基于多变量搜索的加速POWELL算法,在确定的参数空间内,遍历搜索最佳性能点,可以保证最终优化解的全局性。气动反问题求解采用了壁面喷吸气模型。计算案例表明,本文方法的计算时间少,在流动不分离时具有与RANS同等计算精度,为快速开发低速风力机翼型提供了一个有效的设计方法。 相似文献
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研究翼型绕流的转捩预测方法,对于翼型流动细节的精确模拟和气动力的准确计算以及精细化设计均具有十分重要的意义.采用动模态分解(dynamic mode decomposition,DMD)代替线性稳定性理论(linear stability theory,LST)与eN方法结合,不需要求解稳定性方程,成为一种数据驱动的翼型边界层转捩预测新方法,称为DMD/eN方法.在原有方法的基础上,改进了DMD网格线生成方法和扰动放大N因子的积分策略,并将RANS求解器与改进的DMD/eN方法进行耦合,实现了翼型定常绕流转捩预测自动化.采用该方法对LSC72613跨声速自然层流翼型以及NLF0416低速自然层流翼型在不同攻角下的绕流进行转捩预测,转捩点计算结果均与实验值和LST/eN方法吻合良好.该方法计算得到的N值增长曲线与LST/eN方法的包络线也较为吻合,进一步验证了积分策略的正确性.改进的DMD/eN方法可作为自然层流翼型设计的新的有力工具. 相似文献
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应用GAO-YONG可压缩湍流模式数值模拟RAE2822翼型绕流 总被引:3,自引:0,他引:3
应用Gao-Yong可压缩湍流模式,数值模拟RAE2822二维翼型在两种不同来流情况下的跨音速粘性绕流问题.湍流模式的对流项用ROE格式离散,扩散项用中心差分格式离散,空间离散后的控制方程用多步Runge-Kutta显式时间推进格式求解.计算结果预测了翼型表面的压力系数的分布、平均速度剖面、激波的位置、马赫数等值线等情况.同时,对翼型表面激波与边界层相互干扰以及转捩问题进行分析计算,结果表明,Gao-Yong可压缩湍流模式结合适当的数值方法能够成功地模拟翼型跨音速粘性流动.最后,基于Gao-Yong可压缩湍流模式各项异性湍流粘性的机理,初步提出一种预测转捩起始位置的方法. 相似文献
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This paper describes extensive computer-based analytical studies on the details of unsteady flow behavior around airfoils
subjected to flow induced vibration in turbo-machinery. To consider the time-dependent motions of airfoils, a complete Navier-Stokes
solver incorporating a moving mesh based on an analytic solution of motion equation for airfoil translation and rotation was
applied. The drag and lift coefficients for the cases of stationary airfoils and airfoils subjected to flow induced vibration
were examined. From the numerical results in non-coupling case as out of consideration of the airfoil motion, it was found
that the separation vortex consisted of large-scale rolls with axes in the span direction, and rib substructures with axes
in the stream direction. In the coupling simulation including the airfoil motion, both the translation and the rotation displacement
were gradually increased when the airfoil translation and rotation natural frequencies synchronize exactly with the oscillation
frequency of the fluid force. In addition, the transformation from complex structure with rolls and ribs to two-dimensional
aspect of only rolls could be visualized in three-dimensional simulation. 相似文献
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V. P. Zamuraev 《Technical Physics》2009,54(5):749-752
The mechanism of interaction between a pulsed-periodic source of low energy and a closing shock arising near airfoils in transonic
flight is studied. Based on the numerical solution of 2D nonstationary equations of gas dynamics, the evolution of the shock-wave
pattern in the flow about a symmetric airfoil at low-frequency energy input is investigated and the mechanism of interaction
is determined that differs from the generally accepted one, which considers a low-density wake. The new mechanism is not observed
at single input of energy. 相似文献
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A new experimental set-up is proposed to investigate the noise generated by airfoils. It consists of two adjacent plane jets ducted into an anechoic room, and the airfoils under investigation are placed in the median jet. Besides the benefit in the acoustical conditions of the experiments (decrease of the background noise due to the jets, shift of the preferred frequencies of the jets below the range of interest for the airfoil emission), the aerodynamic situation itself is improved (increase in length of the potential zone, decrease of induced flow fluctuations). There is therefore the possibility to investigate airfoil noise with longer chords and higher incident velocities. 相似文献
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Despite becoming increasingly popular in many branches of computational physics, Jacobian-free Newton–Krylov (JFNK) methods have not become the approach of choice in the solution of the compressible Navier–Stokes equations for turbulent aerodynamic flows. To a degree, this is related to some subtle aspects of JFNK methods that are not well understood, and, if poorly handled, can lead to inefficient and unreliable performance. These are described here, along with strategies for addressing them, leading to an efficient JFNK algorithm for turbulent aerodynamic flows applicable to multi-block structured grids and a one-equation turbulence model. Development of globalization strategies for field-equation turbulence models represents one of the key contributions of the paper. Numerous examples of subsonic and transonic flows over single and multi-element airfoils are presented in order to demonstrate the efficiency and reliability of the algorithm. In addition, a number of guidelines are presented to aid in diagnosing problems with JFNK algorithms. 相似文献
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A new method for shape optimization for unsteady viscous flows is presented. It is based on the continuous adjoint approach using a time accurate method and is capable of handling both inverse and direct objective functions. The objective function is minimized or maximized subject to the satisfaction of flow equations. The shape of the body is parametrized via a Non-Uniform Rational B-Splines (NURBS) curve and is updated by using the gradients obtained from solving the flow and adjoint equations. A finite element method based on streamline-upwind Petrov/Galerkin (SUPG) and pressure stabilized Petrov/Galerkin (PSPG) stabilization techniques is used to solve both the flow and adjoint equations. The method has been implemented and tested for the design of airfoils, based on enhancing its time-averaged aerodynamic coefficients. Interesting shapes are obtained, especially when the objective is to produce high performance airfoils. The effect of the extent of the window of time integration of flow and adjoint equations on the design process is studied. It is found that when the window of time integration is insufficient, the gradients are most likely to be erroneous. 相似文献