Two-Phase Fluid Flow Summary

TWO-PHASE FLUID FLOW Fluid Flow Summary The main points from this chapter are summarized below. Two-Phase Fluid Flow Summary The combination of liquid and vapor flowing through a pipe is called two-phase flow. Types of two-phase flow include: • Bubbly flow: there is a dispersion of vapor bubbles in a continuum of liquid. • Slug flow: the bubbles grow by coalescence and ultimately become of the same order of diameter as the tube, generating bullet shaped bubbles. • Annular flow: the liquid is distributed between a liquid film flowing up the wall and a dispersion of droplets flowing in the vapor core of the flow. Core flow oscillations and instabilities can cause: • undesirable mechanical vibration of components. • a reduction in the heat flux required to cause DNB. • interruptions to actual circulation flow. Flow oscillations and instabilities can occur during the following conditions: • core is outside design conditions, power > 150% • mechanical failure, causing flow blockage • inadequate core cooling during natural circulation, such that boiling is occurring Pipe whip is the displacement of piping created by the reaction forces of a high velocity fluid jet following a pipe rupture. Water hammer is a liquid shock wave resulting from a sudden starting or stopping of flow. HT-03 Page 46 Rev. 0