基于本征正交分解的缸内流场仿真校核方法探究

由于直喷式发动机缸内流场具有高湍流和循环变动等特性,因此,发动机三维模型的流场校核显得尤为重要。基于某光学发动机,利用高速粒子图像测速,对发动机缸内流场进行采集,同时利用大涡模拟对其进行三维建模仿真计算,将试验结果用于发动机模型的校核。并基于本征正交分解的方法,提取主要模态,分别从模态和能量的角度,全面对流场进行校核。在校核的基础上,分析了发动机的特征模态和循环变动。通过分析主要模态能量系数的波动,阐述包含大部分能量的流场和局部小涡团上分别的特征差异,提出了基于模态相关性系数的缸内流场仿真校核方法,通过相关性系数体现试验和仿真的主要流场模态占混合本征正交分解的流场模态的权重,进而显示了试验和仿真结果的客观差异,对流场校核的全面性进行了补充。

Calibration Methods of In-Cylinder Flow Field Simulation Based on Proper Orthogonal Decomposition

Due to the high turbulence intensity and the cycle variation of in-cylinder flow field for direct injection engine ,the flow field calibration of three-dimensional model became especially important .The in-cylinder flow field of an optical engine was measured via a high-speed particle image velocity measurement device and the large eddy simulation was conducted at the same time .Then the results were used to calibrate the engine model .Main modes were extracted through proper orthogonal decom-position and the comprehensive calibration of flow field was conducted from the mode and energy aspects .The typical modes and the cycle variation were further analyzed .By analyzing the coefficient fluctuation of main modes and describing the charac-teristic differences of flow field containing most energy and local small eddy ,the calibration method of in-cylinder flow field simulation based on the modal correlation coefficient was put forward .The correlation coefficient showed the weight of main flow field modes for test and simulation in mixed proper orthogonal decomposition modes ,and the real difference between test and simulation was determined ,filling the gaps in flow field calibration .