Film boiling phenomenon is one of the least understood aspects of superfluid helium (He II), which is of both academic and applied interests. In the present study, characteristics of the film boiling in He II are experimentally investigated. Different film boiling states, including noisy film boiling, transition boiling and silent film boiling are studied. It is found that the appearance of the film boiling state depends strongly on the thermal conditions. The general outlooks of the different boiling states are different. The pressure and the temperature oscillations display different features in different boiling state. The pressure oscillation and the temperature oscillation highly correlate with each other in noisy film boiling, and the pressure and the temperature amplitudes are very large. The heat transfer coefficient in the film boiling is measured to evaluate the heat transfer performance. The heat transfer coefficient varies linearly with the immersion depth in noisy film boiling and silent film boiling, and displays a small jump in the transition boiling region. The experiments in the case of the cyclic heat input are also conducted for comparison. The heat transfer characteristics are quite similar in both pulsed and cyclic heat input cases.
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