基于实验数据同化的湍流模型常数标定:含滤网蒸汽阀门通流特性数值预测

为准确预测含滤网蒸汽调节阀通流特性,采用集合卡尔曼滤波算法,通过拉丁超立方抽样生成湍流模型常数的样本库并获得对应流场计算结果,融合部分开度下的阀门蒸汽流动压比-流量实验数据,对k-ωSST湍流模型的常数进行了重新标定。针对独立实验测量所得的流量数据,对比分析计算结果表明:重新标定的模型常数可以有效提高通流特性预测模型的精度,适用于相近开度、不同压比的蒸汽流动工况计算,而对开度相差较大的情形,流量预测误差则较高;不同开度下的阀内流态和涡黏度在模型常数调整前后存在明显差异。本文通过修正模型常数以优化不同工况下涡黏度的分布,从而显著降低阀门通流特性预测误差,这一研究方法对于相关工程设计有很好的借鉴意义。

Calibration of turbulence model constants using measurement data assimilation:prediction of steam valve flow characteristics with filter

To accurately predict flow characteristics of steam control valve with filter,the model constant vectors in k-ωSST turbulence model are recalibrated using ensemble Kalman filter against valve’s flow rate experiment data at several valve openings.In the procedure,Latin hypercubic sampling method is used to perturbate the model constants and generate samples of predicted valve flow rates.Then the samples are assimilated with independent experiment data to update model constant vectors iteratively until convergence is achieved so as to complete the recalibration.In terms of pressure ratio and flow rate measured in independent experiments,the comparison and analysis shows that the recalibrated model constants can be well applied to simulation of steam flow at approximate valve opening but different pressure ratios;this greatly reduces the deviation of valve inlet flow rate between model predictions and experiment measurements,while the configuration with significantly different valve openings is still exposed to notable errors in predicted flow rate.The predicted flow patterns and eddy viscosity determined from simulations with and without the recalibrated model constants vary significantly at different valve openings.Given the fact that optimizing valve flow characteristic prediction via model constant recalibration is made with the optimized eddy viscosity estimation,such methodology provides good reference for related engineering design.