Gas accumulation induced by temperature rise and sudden pressure drop in an inverse U-bend

The gas accumulation occurring in an inverse U-bend due to sudden pressure drop and temperature rise was characterized. The initial conditions of gas accumulation, the changes in accumulated gas volume, and the interface limits were investigated for various liquid velocities, liquid temperatures, and orifice sizes; the liquid temperature was increased from 20 °C in the liquid velocity range from 0.162 to 0.315 m/s. The rise in the liquid velocity corresponded to higher temperature at OGA and rate of gas accumulation. When the liquid velocity exceeded about 0.32 m/s, there was no longer gas accumulation. Under the liquid temperature of 40 ℃, the cavitation and gas accumulation were triggered by sudden pressure drop. The onset conditions of gas accumulation varied depending on the liquid temperature and the orifice size; the higher the liquid temperature and velocity, the faster the gas accumulation.