Simulation of flow around ridge precursors at different angles of attack

The advantages of good stealth and supersonic flight performance make the ridged precursor an ideal configuration for future high-performance fighters and cruise missiles. The ridged precursor has a dominant leeward vortex, and the shape of the precursor can have a great influence on the vortex as well as the aerodynamic forces. Although many research works have been carried out on the static aerodynamic characteristics of ridged forebodies, which have also been applied to engineering practices, the understanding on the flow evolution mechanism and the influence of ridged forebodies at high angles of attack is still insufficient. To overcome the difficulty in simulating separated turbulent flows at high attack angles for ridged precursor aircrafts, the present study adopts the IDDES hybrid turbulence model with a matched unsteady algorithm. This work focuses on the aerodynamic characteristics of ridged precursors at different attack angles, and gives the detailed evolution of flow structures, including the breakdown of the leeward vortex. The ridged precursors with different ridge angles and different ratios of height to width are selected for the computation, and the results show that when the attack angle is small, the leeward vortex of the ridged precursor gradually increases with the increase of the attack angle; above a certain attack angle, the leeward vortex breaks down. For a given attack angle, when the ridge angle becomes smaller, the leeward vortex gets stronger and the vortex lift gets larger. For precursors with the same ridge angle, when the ratio of the height to width for the upper half section becomes smaller, the strength of the leeward vortex gets larger, and the critical attack angle gets smaller, i.e., the precursor vortex breaks down in advance.