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传统的雷诺平均方法(RANS)已经不能满足大范围分离、激波振荡、压力脉动、动载荷等极端工况下的流动预测需求;大涡模拟(LES)、直接数值模拟(DNS)等方法资源耗费多、效率低,离工程湍流问题仍较为遥远。RANSLES混合方法结合了RANS高效率和LES高精度的特点,近期有望大规模应用到工程湍流问题中。首先对现有的RANS-LES混合方法进行了归类,对各自的构造思想、特点进行了分析。然后报告了脱体涡模拟(DES)类方法的发展历程和现状,讨论了使用DES类方法计算分离流动时,对流项离散格式对分离特性、小尺度结构及频谱特性等的影响,并构造了自适应耗散函数。最后介绍了近年来国内外RANS-LES混合方法在宽马赫数范围(马赫数从0.1到20)内的机理研究和工程应用。现有的以DES类方法为代表的RANS-LES混合方法能够较为精细地模拟非定常大分离流动中的复杂现象,但在计算效率等方面还有较大的改进空间;植入式DES方法在模拟全机带部件流动上具有较高的效率和模拟精度,是重要的发展方向。RANS-LES混合方法在动态失速、燃烧、气动弹性、气动噪声、气动光学等与非定常流动密切相关的方面也有广阔的应用前景。
The traditional Reynolds averaged method (RANS) can not meet the demand of flow prediction in extreme conditions such as large-scale separation, shock oscillation, pressure pulsation and dynamic load. Large-eddy simulation (LES) and direct numerical simulation (DNS) Costly, inefficient, turbulent flow from the project is still far away. The RANSLES hybrid approach combines the high efficiency of RANS with the high accuracy of LES and is expected to be applied in large scale to turbulent engineering problems in the near future. Firstly, the existing RANS-LES hybrid methods are classified, and their respective structural ideas and characteristics are analyzed. Then, the development history and status quo of the DES method are reported. The influence of the discrete form of the convection term on the separation characteristics, the small-scale structure and the spectral characteristics are discussed when the DES method is used to calculate the separation flow. Adaptive dissipation function. Finally, the mechanism and engineering application of the hybrid RANS-LES method at home and abroad in the broad Mach range (Mach number from 0.1 to 20) are introduced. The existing RANS-LES hybrid method, which is represented by the DES method, can simulate the complex phenomena in unsteady large-scale separation flow more finely, but there is still much room for improvement in terms of computational efficiency. The implantable DES method It is an important development direction to simulate the flow of components with full machine with high efficiency and simulation accuracy. The RANS-LES hybrid method also has broad application prospects in the fields of dynamic stall, combustion, aeroelasticity, aerodynamic noise, aerodynamic optics and other unsteady flow.