Effect of non-condensation gas on pressure oscillation of submerged steam jet condensation Quanbin Zhao Yuelei Cong Yingchun Wang Weixiong Chen Daotong Chong* Junjie Yan State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, PR China Abstract: The effect of air with low mass fraction on the oscillation intensity and oscillation frequency of a submerged steam jet condensation is investigated under stable condensation region. With air mixing in steam, an obvious dynamic pressure peak appears along the jet direction. The intensity peak increases monotonously with the rise of steam mass flux and water temperature. Peak position moves downstream with the rise of air mass fraction. Moreover, when compared with that of pure steam jet, the oscillation intensity clearly decreases as air is mixed. However, when water temperature is lower than approximately 45 °C, oscillation intensity increases slightly with the rise of air mass fraction, and when water temperature is higher than 55 °C, the oscillation intensity decreases greatly with the rise of air mass fraction. Both the first and second dominant frequencies decrease with rise of air mass fraction. Finally, effect of air mass fractions on the oscillation power of the first and second dominant frequency bands shows similar trends. Under low water temperature, the mixed air has little effect on the oscillation power of both first and second frequency bands. However, when water temperature is high, the oscillation power of both first and second frequency bands appears an obvious peak when air mass fraction is about 1%. With further rise of air mass fraction, the oscillation power decreases gradually. Keywords: submerged steam jet; condensation oscillation; air mass fraction; oscillation dominant frequency; oscillation power 1 Introduction Steam submerged jet condensation has been used widely in the industry because of its characteristics of high heat transfer and mass exchange capacity. Steam jet condensation system has the characteristic of passive, no motion part and no electrical control. Therefore, it is widely used in the fast heat discharge systems and residual heat reutilization industry applications, such as pressure relief pool in boiler water reactor, refueling water storage tank in advanced light water reactor, steam ejector and steam water direct contact heat exchanger. However, steam submerged jet can cause pressure oscillation in the water. Pressure oscillation leads incessant load on the water tank or other apparatus in the tank. Specifically, when pressure oscillation frequency is close to the natural frequency of the water tank or relevant apparatus in pool, the resonance phenomenon happens. This phenomenon should be taken into account and avoided in the system design. Thus, the original experimental data of steam jet condensation oscillation is needed in the design database of nuclear reactor plant or other steam jet condensation systems. Numerous scholars have investigated the jet condensation oscillation for many years. Chan (1978) measured the dynamic pressure impulse of submerged steam jet with sonic speed. They found that the oscillation frequency decreased with the rise of water temperature and nozzle diameter. Moreover, the interface oscillation caused by expansion and compression was more © 2016. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/