Experimental investigation of high-temperature water vapour ventilated supercavitation

Abstract

In the current landscape of underwater vehicle development, high-tech advances are increasingly being utilised, especially in the application of high-speed underwater equipment. Based on the concept of water ram engine operation, the formation of a ventilated supercavity by converting seawater into high-temperature water vapour has the potential to reduce the consumption of ventilating gases. However, the kinetic process that promotes the formation of a supercavity by ventilating it with high-temperature water vapour remains unexplored. This study attempts to bridge this knowledge gap by carefully investigating the cavitation flow around an axisymmetric object under various high-temperature water vapour ventilation conditions. Experiments conducted in a cavitation tunnel equipped with a high-temperature water vapour generator showed that the formation of a transparently ventilated supercavity requires a significant increase in the ventilation rate compared to the ventilation rate facilitated by room-temperature non-condensable gases. The injection of high-temperature water vapour produces perturbations along the cavity boundaries, thereby triggering interfacial instability, a phenomenon that is not present in super-cavities generated by non-condensable gases. Further observations revealed a correlation between the elevated ventilation temperature and elevated cavity boundary instability. In addition, the stability of a high-temperature water vapour ventilated supercavity (HWVVS) exhibits high sensitivity to external environmental conditions. The irrational pairing of the ambient cavitation number and ventilation volume poses a potential risk of supercavity collapse.