An experimental investigation of the characteristics of explosive boiling of subcooled water on a hot surface under conditions of change of boiling modes

A procedure of estimating the area of contact between cold water and a hot hemispherical surface is developed and described. Synchronous measurements of pressure pulses in liquid, the temperature of a body, and characteristics of contact between a heated body and a coolant are performed under conditions of abrupt change of boiling modes (from film to nucleate boiling). Characteristic features of the investigated processes are determined, which are largely defined by the temperature of the hemisphere, by its thermophysical properties, and by the presence of surface oxide films. It is found that the maximal value of the amplitude of pressure pulses, which may be as high as $\sim1$ MPa in the experiments, is observed in the region of temperatures of the hot body which are close to the temperature of limiting superheat of water. The dependences are obtained of the rate of spreading of liquid and of the time of delay of its explosive boiling from the instant of boiling on the temperature of the hemisphere.