VA-111 Shkval Rocket: Supercavitation inject, Mass Transfer

Description

This project extends a previous simulation of the VA-111 Shkval supercavitating torpedo in ANSYS Fluent by incorporating mass transfer to capture cavitation effects. The objective is to analyze how cavitation influences the vehicle's hydrodynamic performance and to compare it against the non-cavitating case. The Shkval is a high-speed underwater vehicle, making this a distinctly marine and naval engineering problem, where supercavitation is exploited to dramatically reduce drag and enable exceptional underwater speeds.

The geometry and mesh remain the same as in the previous study: the VA-111 Shkval was created in SpaceClaim and meshed in Fluent Meshing, producing a polyhedral mesh of 257,000 cells.

Methodology

The simulation uses a transient, pressure-based solver with the k-ε turbulence model, initialized from a steady, no-mass-transfer case. To capture the cavitation, the Zwart-Gerber-Belamri model is enabled, which accounts for the mass transfer between the liquid and vapor phases. This cavitation model is coupled with the VOF multiphase model to accurately represent the formation and collapse of the vapor cavities that surround the vehicle.

Conclusion

The results reveal significant differences in the flow field and performance characteristics once cavitation is taken into account. The mass transfer rate contour identifies the regions where cavitation occurs, with the highest rates near the vehicle's nose and along its body. The volume fraction contour shows the vapor cavities enveloping the vehicle, which effectively reduce the wetted area.

The pressure distribution exhibits a low-pressure region near the nose that triggers the formation of the vapor cavities, and the velocity magnitude contour shows higher velocities within the cavity than in the surrounding liquid — confirming the drag-reduction mechanism of supercavitation. The turbulent kinetic energy contour highlights elevated turbulence in the wake, caused by the collapse of the vapor cavities; this turbulence can add to the drag and affect the vehicle's stability.

Overall, incorporating mass transfer and cavitation modeling provides valuable insight into how cavitation shapes the hydrodynamic performance of the VA-111 Shkval. The results clearly demonstrate the benefits of supercavitation: by forming vapor cavities that shrink the wetted area, the vehicle achieves a marked reduction in skin-friction drag — the key principle behind high-speed underwater travel in marine engineering.