Theoretical Analysis and Numerical Study for Spin Jet Formation Performance

Small-caliber shaped charges rely on rotation for flight stability; however, this rotation impacts the jet formation performance, leading to radial dispersion and fragmentation of the jet. This study establishes a theoretical model to analyse the rotating jet formation process, based on classical jet formation theory. A smoothed particle hydrodynamics (SPH) numerical simulation model, calibrated with existing experimental data, was employed to simulate the formation process of rotating jets, and revealed the interplay between the jet’s axial and tangential velocities. Based on these findings, a theoretical analysis model for rotating jet formation was developed under specific assumptions to predict the jet velocity distribution, jet radius distribution, and fracture time. The theoretical results indicate that regardless of the initial angular velocity, the jet does not fracture instantaneously; on the contrary, it fractures progressively from the tip to the tail. The discrepancies between theoretical predictions and numerical simulations for the jet tip velocity and fracture time were 4.2% and 4.2 μs, respectively, validating the accuracy of the theoretical model.