Studying multiphase flow around a vehicle moving freely to the water surface

The paper provides an experimental study of a multiphase flow around models in a large high-speed hydrodynamic tunnel with a vertical working section. Experimental dependences of drag coefficients on the cavitation number for vertical cavities are obtained. The results of cavitation flow around bodies of revolution in a vertically descending fluid flow are considered. A methodology for calculating the shape of vertical cavities under the slender-body theory is proposed. Relationships suitable for engineering evaluation are obtained for very long cavities. Numerical simulation of underwater motion is performed with models moving vertically in a nonstationary cavitation flow. The hydrodynamic loads can be evaluated through the determination of the nonstationary boundaries of a gas cavity and a linear load on a water-flown aft. The predicted results are compared with the experimental data. Validation and verification are performed by comparing the analysis results with the experimental data. The applicability of the proposed method to the determination of the hydrodynamic parameters of vehicles under multiphase flow is demonstrated.