Experimental and theoretical study on the second dominant frequency in submerged steam jet condensation

Condensation oscillation of steam jet is of high importance for industrial facility. In this study, the mechanism and propagation characteristic of the second dominant frequency is investigated. Firstly, the second dominant frequency is found under all the test conditions based on frequency spectrum. The second dominant frequency decreases with the rise of water temperature and steam mass flux. Then, the second dominant frequency is proved to be generated by the separated steam bubbles oscillation based on the bubble oscillation theory. And the theoretical oscillation frequency equation of separated steam bubble is used to predict the second dominant frequency, the predicted deviation ranges from −17% to 6%. Furthermore, the propagation characteristic of the second dominant frequency is investigated, and a theoretical propagation equation for the second dominant frequency is derived. Then, the axial and radial distribution characteristic of oscillation amplitude and energy of the second dominant frequency are analyzed and researched. In the downstream flow field and the radial direction, the propagation characteristic of steam bubble oscillation wave is well corresponding to the predicted results. However, in the upstream flow field, due to the effect of steam plume, the oscillation amplitude and energy of the second dominant frequency attenuate rapidly and the experimental data are much smaller than the predicted value.