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在对低速气体进行计算流体力学(CFD)数值模拟时,通常忽略气体的可压缩性。当计算体系中存在较大温差和较大组分浓度差时,不可压缩近似会因带来很大计算误差而失效。针对此问题,低马赫数方法通过将实际压力拆分为热力学压力和动力学压力的方式,将物性参数与热力学压力联系起来,在对不可压缩流动求解器进行较小改造后,较准确地处理低马赫数下的可压缩流问题。利用Code_Saturne程序实现该模型,并针对空气射流破坏轻密度气体分层现象进行模拟。首先通过网格敏感性分析,选定中等密度网格为计算网格;然后在比较不同算法的模拟结果中发现,采用低马赫数方法可以明显提高计算精度。最后,利用模拟结果,对空气射流破坏氦气分层实验中氦气的水平分布情况进行分析和讨论。
Computational fluid dynamics (CFD) numerical simulations of low-velocity gases generally neglect the compressibility of the gas. When there is a large temperature difference and a large concentration difference in the calculation system, the incompressible approximation will fail due to the large calculation error. In response to this problem, the low Mach number method is based on the physical pressure split into thermodynamic pressure and dynamic pressure, the physical parameters associated with the thermodynamic pressure, the incompressible flow solver was slightly modified, more accurate treatment Compressible Flow Problems at Low Mach Numbers. The Code_Saturne program is used to implement the model and simulate the phenomenon of air jets destroying light density gas stratification. First of all, through the grid sensitivity analysis, the medium density grid is chosen as the calculation grid. Then, the simulation results of different algorithms are compared. It can be found that the low Mach number method can obviously improve the calculation accuracy. Finally, the results of the simulation are used to analyze and discuss the horizontal distribution of helium in the helium detonation experiment.