Flow Characteristics and Status of CFD Hydrodynamic Model Development in Sudden Contraction Manifold/Orifice Configurations

摘要

Applications of sudden contraction manifold/orifice configurations range from city water drainage, diesel and gasoline fuel injection systems, and high speed underwater torpedoes, as well as rocket engine injector manifold flow passages. While the literature is extensive and dates back more than a century, the details of the flow characteristics as well as the quantitative impacts on losses are still sketchy at best. A clear understanding of the detailed process flow characteristics and fluid state in the entrance region and throughout the flow path to the orifice exit is a vital element in the ability to more knowledgeably predict these loss coefficients as well as orifice exit flow characteristics. More recent studies have been focusing on the details of the processes in an attempt to better understand the governing variables and quantify flow characteristics impacts. These processes are known to be dependent on orifice configuration, and there are a myriad of possible manifold/orifice configurations with abrupt contraction whose selection depends on both the application and manufacturer preference. The recent generation of empirical correlations has allowed limited verification of hydraulic CFD code predictions and status of their development. However, the data necessary to verify code prediction of orifice exit characteristics and hydraulic flip are lacking. Complete verification allowing for prediction of the global and spatial processes as well as hydraulic flip is vital to the goal of achieving predictive capability of spatial and global spray distributions. Due to the importance of achieving reliable hydraulic CFD models, a brief discussion is included of attempts to verify CFD code prediction with experimental data.