一种尺度无关的滤波曳力模型的固气密度比影响分析

Infl uence Analysis of the Solid-gas Density Ratio on a Scale-independent Filtered Drag Model

气固两相流系统的物性参数一般会影响滤波曳力模型进而影响其应用,但固气密度比对滤波曳力的影响规律尚不明确。本文采用一种尺度无关滤波曳力建模方法对一定固气密度比范围(200~2015)的细网格模拟数据进行分析发现,采用气相压力梯度、当地固含率和周边固含率(三倍于滤波尺度的滤波固含率)分类后的滤波曳力具有尺度无关和对密度比变化不敏感的特性。因此本文基于不同固气密度比细网格数据构建了系列滤波曳力模型,先验和后验分析显示,相比于文献报道的物性修正曳力模型,本文所构建的介尺度曳力模型的预测结果更加接近细网格结果和实验结果,且具有尺度无关和对密度比变化敏感度低的特点。

The material parameters of a gas-solid two-phase flow system generally affect the filtered drag model and its application,but how the solid-gas density affects the filtered drag force is still unclear.In this paper,the fine-grid simulation results in a range of solid-gas density ratios(200~2015)are analyzed by a scale-independent filtered drag modeling method.It is found that,the filtered drag force classified by local gas pressure gradient,filtered solid volume fraction and the surrounding filtered volume fraction(the filtered volume fraction at the scale whose side length is three times of the filter size)shows scale-independent and insensitive to density ratio variations.Therefore,new filtered drag models based on fine-grid simulations with different density ratios are established in this paper and the prior and posterior tests suggest that the predictions of our models are closer to the fine-grid results as well as the experimental data than the material parameters correction models reported in the literature.The models also exhibit scale-independent features and low sensitivity to density ratio variations.