243901771-Mek4450-Ife-Day1-Lesson2.pdf - Multiphase Flow...

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Multiphase Flow Technology Agenda 22 nd of October 2013 Introduction to multiphase flow Terms & regimes Conservation equations Stratified flow Applications Slug flow 22.10.2013
22.10.2013 Lecture notes IFE, 2013.10.22 Jan Nossen & Karin Hald MEK 4450 Terms & Notation Multiphase flow – Applications Conservation equations
A Multiphase flow terms, notation 22.10.2013 g A o A w A Gas Oil Water Void fraction : Oil holdup : Water holdup: Total holdup: w o w w o o g A A A A A A β β β β β α + = = = = / / / U g U o U w
Multiphase flow terms, notation 22.10.2013 z y G Name Dimension Legend . e J/kg Specific internal energy h J/kg Specific enthalpy p Pa Pressure S m Wetted length ρ kg/m 3 Density α, β, γ - Gas, liquid bulk, droplet fractions τ Pa Shear stress ψ E kg/(sm 3 ) Droplet entrainment rate ψ D kg/(sm 3 ) Droplet deposition rate
5 Real stratified flow Continuous gas Gas bubbles in oil Gas bubbles in water Continuous oil Oil drops in gas Oil drops in water Continuous water Water drops in gas Water drops in oil Thin liquid film on upper wall wd w wc od o oc w o g β γ β β γ β α α α o γ w α o α oc β od β wd β Thin film wc β g α
Flow regimes Depend on phase velocities phase quantity pipeline orientation flow system gas/liquid liquid/liquid 22.10.2013 oil gas IFE Lab data
Flow regimes: Near horizontal Gas/liquid regimes: Stratified Annular Slug Bubble Liquid/liquid regimes: Stratified (separated) Partly separated/dispersed Dispersed oil/water flow
Flow regimes: Near vertical Gas/liquid regimes: (a-b) bubble flow (c-d) slug/churn flow (e) annular flow Liquid/liquid regimes: Dispersed .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: .: a b c d e
Transition criteria 22.10.2013 Large Wave Stratified Slug Bubble Liquid velocity Gas velocity
Flow regime transitions The most important flow regime transition in pipelines is from stratified flow to slug flow Two conditions must be fulfilled for slug flow to exist: Stratified flow must be unstable ( Kelvin-Helmholtz instability ) Slugs that are formed must be able to grow ( Minimum slip ) The Kelvin-Helmholtz criterion tells that the stratified flow region gets smaller with increasing pressure Experimental data show that the slug flow region also gets smaller with increasing pressure For high pressure we get a region of large wave flow in between stratified and slug

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