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Effects of vortex generator (VG) on the flow field in a flush-intake duct for waterjet propulsion are investigated numerically under various navigation conditions. Flow’s Reynolds-averaged Navier-Stokes equations (RANS) are solved with the SST-Kω turbulence model. Four VG blades are installed at the ship bottom ahead of the intake entrance. The VG blade is rectangular shaped with a height of 0.1D, a length of 0.3D, and an angle of attack of 20°. Results show that under the forward moving condition, VG device effectively restrains the flow separation on the duct ramp side and improves the section uniformity at intake exit under low inflow velocity ratio (IVR) condition. The duct efficiency gets improved over a wide IVR range. Under the oblique moving condition, there is no separation region on the duct ramp side at low IVR, but significant vortex appears on the lip side. VG device does not introduce any obvious extra negative effects on the hydraulic performance.

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In this paper, a multi-physics field coupled finite element model for the motion of projectile in a hot barrel is proposed and validated by muzzle velocity test and barrel temperature test. The model includes heat transfer analysis, explicit dynamic analysis and investigates the in-bore motion of the projectile under different barrel temperature conditions. It is pointed out that, with the increase of barrel temperature, the radial displacement of the projectile centroid increases, the consistency of the radial velocity of the projectile centroid becomes worse, and the swing angle increases significantly. This work can contribute to further studies on anomalous dispersion mechanism and improvement of firing accuracy.