Numerical study on the thermal-hydraulic characteristics of the choked flow through micro cracks for various conditions

It's of great significant to figure out the detailed mechanisms of the leak flow through micro-crack. Three-dimensional numerical simulation provides a visual and effective access to elaborate the complex leak phenomena and characteristics by taking advantages of full-size crack passages modeling. In this study, three-dimensional numerical simulation was developed by establishing geometrical and thermal-hydraulic models. The crack morphologies (COD, crack length, crack depth and cross section) were simulated, and various thermal-hydraulic conditions (liquid, superheated vapor, supercritical fluid and multiphase) were considered. The numerical method was validated by the experimental results both from this study and literatures. What's more, the leak flow phenomena such as flow pattern, compression, flashing and choking were obtained based on the validated numerical simulation. Influences of crack morphologies and thermal-hydraulic parameters on flow characteristics were analyzed. The flow mechanisms of flashing, phase interaction and critical flow were elaborated using the three-dimensional numerical method. This study gives a comprehensive and thoughtful investigation on the choked flow through micro-crack, revealing the detailed thermal-hydraulic phenomena and mechanisms of the flow through micro cracks for various crack morphologies and conditions. Therefore, this study provides an effective approach and a theoretical foundation for understanding the choked flow mechanisms through cracks.