Experimental Investigation of Early Response of Hot Water Rapid Blowdown in Separated Pipeline

Abstract In this study, a series of separate effects tests are carried out to investigate the phenomena of the early response of the blowdown process in the ruptured pipe. The experimental section is a 50 mm nominal stainless steel pipe about 1600 mm long. Several high-precision piezoelectric sensors are placed along the pipe and the outside space near the rupture point with a data acquisition frequency of up to 20 kHz. Two methods are used for the postulated pipe rupture simulation: one using a quick-opening solenoid valve, and the other is realized by a thin glass cap and shatter trigger. Based on the experiments, pressure distribution and its time trends are obtained during the rapid blowdown process with various initial conditions, including different pressures and subcooling degrees. The characteristics of different stages in depressurization are identified, and some other vital parameters, such as the rate of depressurization and the initial discharge speed are also analyzed. In addition, the time response curve of back pressure in the outside space is recorded, and the flashing of superheated water during the blowdown is filmed. Moreover, the initial speed of the discharge flow is calculated after the data processing. The results of the tests help to understand the transient blowdown process and provide verified data for the simulations. It also provides a foundation for future experiments under higher working conditions and for developing boundary models used in analysis code.