Experimental investigation of side-discharge sparger on pressure oscillation in steam jet condensation

•Influences of the side-discharge sparger in DCC were experimentally investigated.•A regime map is presented for steam jet condensation through a side-discharge sparger.•Temperature has a greater effect on the regime boundary due to the side-discharge sparger.•Rapid increase of a dominant intensity indicates an entry of the bubbling regime. Experiments were conducted to investigate the pressure oscillation of steam jet condensation through a side-discharge sparger in stagnant water. Simultaneous analysis based on the synchronous measurement in the time domain was conducted between pressure oscillation and steam interfacial behaviors, and quantitative discussion about the intensity was taken according to the power spectrum of pressure oscillation. First, a regime map suitable for a sparger of 16 mm was presented and the bubbling, chugging, and jetting regimes were observed in this experiment. Compared with other regime maps, the bubbling regime is more narrow in the range of the steam mass flux when it is at low temperature, while is wider at high temperature. Second, it was found that different frequencies dominate the pressure oscillation under different conditions named the collapse frequency, the condensation frequency, and the generation frequency. The collapse frequency created by the collapse of detached bubbles prevails in the region with the temperature higher than 75 °C, while the condensation frequency induced by the condensation of bubbles controls the pressure oscillation in regions with the temperature lower than 60 °C. The generation frequency caused by the generation of bubbles mainly appears in the bubbling regime and is the secondary influence of pressure oscillation. This work provides a better understanding of steam jet condensation and could be helpful for the analysis of accident scenarios of pressure suppression systems.