中文摘要：

In this study,a suitable CFD(computational fluid dynamics)model has been developed to investigate the influence of liquid height on the discharge coefficient of the orifice-type liquid distributors.The orifice flow in different diameters and liquid heights has been realized using the shear stress transport(SST)turbulence model and the Gamma Theta transition(GTT)model.In the ANSYS CFX software,two models are used in conjunction with an automatic wall treatment which allows for a smooth shift from a wall function(WF)to a low turbulent-Re near wall formulation(LTRW).The results of the models coupled with LTRW are closer to the experimental results compared with the models with WF,indicating that LTRW is more appropriate for the prediction of boundary layer characteristics of orifice flow.Simulation results show that the flow conditions of orifices change with the variation of liquid height.With respect to the turbulence in orifice,the SST model coupled with LTRW is recommended.However,with respect to the transition to turbulence in orifice with an increase in liquid height,the predictions of GTT model coupled with LTRW are superior to those obtained using other models.

英文摘要：

In this study, a suitable CFD（computational fluid dynamics）model has been developed to investigate the influence of liquid height on the discharge coefficient of the orifice-type liquid distributors.The orifice flow in different diameters and liquid heights has been realized using the shear stress transport（SST）turbulence model and the Gamma Theta transition（GTT）model.In the ANSYS CFX software, two models are used in conjunction with an automatic wall treatment which allows for a smooth shift from a wall function（WF）to a low turbulent-Re near wall formulation（LTRW）.The results of the models coupled with LTRW are closer to the experimental results compared with the models with WF, indicating that LTRW is more appropriate for the prediction of boundary layer characteristics of orifice flow.Simulation results show that the flow conditions of orifices change with the variation of liquid height.With respect to the turbulence in orifice, the SST model coupled with LTRW is recommended.However, with respect to the transition to turbulence in orifice with an increase in liquid height, the predictions of GTT model coupled with LTRW are superior to those obtained using other models.