TWO-PHASE FLUID FLOWFluid FlowSummaryThe main points from this chapter are summarized below.Two-Phase Fluid Flow SummaryThe combination of liquid and vapor flowing through a pipe is called two-phaseflow.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 thesame order of diameter as the tube, generating bullet shapedbubbles.• Annular flow: the liquid is distributed between a liquid film flowing up the walland a dispersion of droplets flowing in the vapor core of theflow.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 occurringPipe whip is the displacement of piping created by the reaction forces of a highvelocity fluid jet following a pipe rupture.Water hammer is a liquid shock wave resulting from a sudden starting or stoppingof flow.HT-03 Page 46 Rev. 0
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