Evaluation and sensitivity analysis of three-dimensional numerical simulation for aerated deflector-generated jets in spillways


 Aeration is an efficient way to prevent cavitation erosion of discharge structure and alleviate damage to trajectory nappe on downstream energy dissipator. Due to the complexity of aeration jet, it is still a big challenge to understand aeration mechanism at the water-air interface. This study applied the two-fluid model to simulate three-dimensional entrainment characteristics of jet flow, and also analyzed effects of bubble size, wall roughness, drag force model, turbulence model, and numerical model dimension on clear-water length. Results reveal that the two-fluid model can accurately and effectively simulate clear-water length, thickness variation, and average cross-section air concentration of jet flow with maximum error of 4.1, 6.5 and 4.2% (x = L1, defining clear-water length with 1% air concentration as L1), respectively. Wall roughness height has a crucial influence on clear-water length. Taking L1 as an example, clear-water length decreases by 13.9% when roughness height increases from 0 to 3 mm. The drag models and bubble particle sizes affect clear-water length only when profile aeration concentration is greater than 15%. Turbulence model and numerical model dimension have a minor effect on clear-water length.