Experimental study on the characteristics of pressure drop oscillations and their interaction with short-period oscillation in a horizontal tube

Long-period oscillations (pressure drop oscillations) and short-period oscillations (superimposed density wave oscillations) have been observed in many studies. However, under which condition the long-period oscillations with superimposed short-period oscillations and long-period oscillations are occurring remains unknown particularly in horizontal systems. In this work, the occurrence of long-period oscillations with superimposed short-period and long-period oscillations are experimentally studied in a horizontal heated tube. It has been observed that long-period oscillations with superimposed short-period oscillations are apparently occurring in the middle of the negative slope of the pressure and mass flux internal system curve. Furthermore, as the inlet temperature subcooling is decreased the short-period oscillations disappear. Pressure drop-mass flux limit cycles are also shown for illustrating the interaction of the oscillations.