Study of Hydrofoil Boundary Layer Prediction with Two Correlation-Based Transition Models

In the realm of marine science and engineering, hydrofoils play a pivotal role in the efficiency and performance of marine turbines and water-jet pumps. In this investigation, the boundary layer characteristics of an NACA0009 hydrofoil with a blunt trailing edge are focused on. The effectiveness of both the two-equation gamma theta (gamma-Re theta t) transition model and the one-equation intermittency (gamma) transition model in forecasting boundary layer behavior is evaluated. When considering natural transition, these two models outperform the shear stress transport two-equation (SST k-omega) turbulence model, notably enhancing the accuracy of predicting boundary layer flow distribution for chord-length Reynolds numbers (ReL) below 1.6 x 106. However, as ReL increases, both transition models deviate from experimental values, particularly when ReL is greater than 2 x 106. The results indicate that the laminar separation bubble (LSB) is sensitive to changes in angles of attack (AOA) and ReL, with its formation observed at AOA greater than 2 degrees. The dimensions of the LSB, including the initiation and reattachment points, are found to contract as ReL increases while maintaining a constant AOA. Conversely, an increase in AOA at similar ReL values leads to a reduced size of the LSB. The findings are essential for the design and performance optimization of water-jet pumps, particularly in predicting and flow separation and transition phenomena.