Response Analysis of Pressure Reduction in Cooling Cavitation in a Closed Pipe Filled with Hot Water

When a closed pipe filled with hot water is cooled, a cavity is generated in the pipe under pressure reduction due to large thermal contraction of water. In this paper, it was made clear that the transient response of pressure reduction in the above cooling cavitation shows the undershoot, and the response was modeled and formulated by the air desorption from the liquid into the cavity. The model parameters identified experimentally were investigated, and the time constant of air desorption sucked through the interface and the time constant of air diffusion within the liquid are obtained as the expressions in terms of the initial total air mass. Comparing the experimental and the calculated results, it was found that the minimum pressure and the final equilibrium pressure are proportional to the initial total air mass, and that the time at the minimum pressure is inversely proportional to the initial total air mass.