Study of pressure oscillation during noisy film boiling in He II

In this paper we study the cause of loud audible noise generation during noisy film boiling in He II. Measurement of the pressure oscillation as well as a visualization study is conducted for this purpose. As a result, it is found that loud audible noise is repeatedly generated at each instance of explosive evaporation of He II which comes into direct contact with an overheated heater surface after a vapour bubble crush. The pressure oscillation measurement over a wide range of hydrostatic pressure also revealed that three film boiling modes appear in He Il: boiling in subcooled He II (referred to as subcool boiling); noisy boiling; and silent boiling, as the hydrostatic pressure decreases. However, very close to the lambda-temperature, subcool boiling makes a direct transition to silent boiling without noisy boiling. Noisy boiling does not appear in subcooled He II, where subcool boiling appears with very weak audible noise of very high frequency. (C) 1997 Elsevier Science Ltd.