Thermodynamic characteristics of the hot-temperature cavity generated by the spark discharge in saline water

Spark discharge in saline water can generate cavity oscillating violently. However, the thermodynamic characteristics of such a cavity is still unclear owing to the complex mechanism behind it. In this study, a systematic model is developed with the considerations of thermal radiation and mass transport, which can successfully evaluate the thermodynamic properties of the spark-induced cavity in saline water. The physical parameters related to the mass transport are identified by comparing with the experimental measurements. By using the validated parameters, we find that the thermal radiation and the condensation process cannot be ignored, and the number of water molecule increases at the first collapse point. In addition, the maximum cavity size increases with increasing absorption of thermal radiation, but decreases when the condensation coefficient increases. Increasing the discharge energy and ambient temperature are found to help generate larger cavity. The inner temperature and pressure at the collapse phase increases with the increase of the discharge energy, whereas decreases when the ambient temperature increases. Furthermore, the minimum temperature at the first maximum size is up to 3000 K under 0.1 MPa, and reaches 8000 K when the ambient pressure is larger than 1 MPa. Thus, we believe the spark-induced cavity in saline water is hot, at least during the first oscillation cycle.