TransAT for Multiphase Flow in Pipes & Risers

Transcription

1 TransAT for Multiphase Flow in Pipes & Risers Djamel Lakehal (July, 2013) ASCOMP GmbH, Zurich

2 Outline Multiphase flow in pipelines Slug flow in horizontal pipes Slug flow in inclined pipes Slug flow with sand Slug/churn/annular flow in risers

3 Multiphase flow in pipes

4 Flow regime map Vertical pipe flow Horizontal pipe flow

5 Slug capturing and separation

6 Validation of base LS approach for interfacial (wavy) flows

7 The Thorpe experiment Experiment by Thorpe (J Fluid Mech., vol 39, 25-48, 1969) Interesting because purely hydrodynamic, simple geometry and Bc s Limited results to most amplified wave length, critical velocity difference

8 The refurbished experiment (UCL, Belgium: J-M. Seynhaeve, Y. Bartosiewicz) Calculated acceleration ramp to minimize initial perturbations High speed camera PIV (2D and stereoscopic) Fluids fully characterized in house (surface tensions, densities, viscosities)

9 Flow visualization

10 Comparison CLICK ON MOVIE

11 Comparison

12 The HAWAC setup (FZD Germany, C. Vallé)

13

14 Comparison Picture sequences at JL = 1.0 m/s and JG = 5.0 m/s with t = 50 ms (depicted part of the channel: 0 to 3.2 m after the inlet)

15

16 Slug formation in horizontal pipes

17 Slug formation: 1- ASHRAE case (Exp. Martin) Slug formation in an air-water flow. Important features : flow pattern: e.g. from stratified to slug (Kelvin-Helmholtz instabilities) Slug formation threshold Pressure drop and slug speed

18 Exp. of Martin (2005) -BFC grid & parallel blocks - L = 6.3m; D=0.14m - J L =0.5m/s & J G = 14m/s. - Void fraction 50% - V-LES & LES for turbulence

19 3D slug formation CLICK ON MOVIE

20 Time (Seconds) Slug speed Nicklin et al. (1962) Collins et al. (1978) Exp. Martin et al. (2005) U 1.2U Dg / s m l g l 0.8 Liquid Temperature : -45 C; Liquid Depth : 76.2 mm PACE1 PACE2 PACE3 PACE4 PACE5 Gas Liquid Slug Gas Liquid V Liquid PCB4 PCB1 PCB2 PCB U = dx/dt = 10.8 m/sec (dm/dt = kg/sec) U = dx/dt = 9.4 m/sec (dm/dt = kg/sec) U = dx/dt = 7.1 m/sec (dm/dt = kg/sec) Location x (Meters)

21 Slug formation: 2- Imperial College WASP case Air Water Physical Parm. Air water Density(kg/m³) Viscosity(Pa s) ( at 25 C) (at 25 C) Surface tension(n/m) (at 20 C)

22 Experimental vs. CMFD of water holdup Exp. (top) vs. CMFD water holdup results for U sl = 0.611m/s and U sg = 4.64m/s. inlet pressure= 1atm (Probe location from 0.76m to 3.56m)

23 CMFD 3D results: Slug forms & shapes (16m) Initial slugs: at x < 5m large slugs, or better, operating slugs Scale ~ 2-4 D Hold-up = 1

24 CMFD 3D results: Slug forms & shapes (16m) Next slugs: at x > 5m disturbance slugs Scale ~ 1 D Hold-up ~

25 CMFD 3D results: Slug signal (16m)

26 Sand Transport in pipes

27 Sand Transport & Corrosion Gas Water/Sand CLICK ON MOVIES

28 Slug formation in inclined pipes

29 Slug flow up an incline (for CHEVRON USA) Objective: Simulate slug flow up an incline for 3 different size pipes (2, 4 and 26 ), and estimate the reentrainment criteria for removing a settled solids bed.

30 Surface deformation

31 Level Sets method with V-LES CLICK ON MOVIES

32 Droplet Entrainment in stratified twophase pipe flows

33 LEIS of the flow in a periodic pipe Flow conditions: - Domain: 3D x 1D - Grid: 46x96x96 - Re_b = Air mass flowrate = 600 kg/hr - Water mass flowrate = kg/hr - Volume flow rate of water is 1/50 of that of air. Click on movie to play

34 The practical context Air-water flow Wetting mechanism Uair=20 m/s ; Uwater=0.02 m/s; Pipe diameter = m Courtesy: Badie & Hewitt Imperial College London

35 LEIS of a space evolving flow in a pipe Click on movie to play Flow conditions: - L = 5m; D = 0.5 m - Splitter plate at inlet: l = 16cm - Water and air - U G = 20 m/s; U L = 0.2 m/s. - Water cut: h/d = Ref = 7050 Computational parameters - IST Grid 1: cells - CPU: 39H on a Dell PC (16 cores) - BFC Grid 2: 1.6 million cells (580x 58x54) - High order schemes: 2nd order time; Quick scheme for convection

36 LEIS of droplet entrainment in a pipe

37 Hydrocarbon flow in vertical pipes & risers

38 Riser flow: The issues The main Issues: flow regime map, pressure drop & heat transients Reality: Subsea flow analysis

39 Two-phase flow in a pipe (Szalinski et al. 2010) Dispersed flow in a pipe, experiment of Szalinski et al., Chem. Eng. Sce, (2010) 2D axisymmetric steady & unsteady grid cells Mixture Algebraic Slip Model Tomiyama lift & drag coeff. correlations Turbulence: URANS (results shown)

40 Case 1 & 2: bubbly flow

41 Case 3: Slug-bubbly flow Click on movie to play

42 Slug-bubbly flow structures Evolution of slug flow at different instants.

43 Normalized SGS viscosity in the Taylor bubble wake

44 Pressure drop and frictional velocity Instantaneous pressure drop along the pipe (left panel), and mean pressure drop (right panel): single-phase vs. slug flow Instantaneous wall frictional velocities along the pipe

45 Annular Flow Regime (very thin film) Annular film flow experiment of Zhao and Hewitt (2012, Imperial College London).

46 Annular flow case Flow measurement conditions V G (L/min) Re G (10 4 ) Re L V L (L/min) Visualized ripple wavy and disturbance waves flow regimes

47 Thick-film annular flow (VLES + LS) Flow conditions: - D = m - L = 4 m - Water and air - V G = 2000 L/m (instead of 1650 L/min), Re G = 8.55 x V L = 70 L/m (instead of 1 L/min), Re L = 4.22 x Initial film: h/d = 0.04 Computational parameters & model - IST Grid : (still medium) - Comp. Time: 49H on 64 proc. (MPI parallel) local cluster - Level Set - V-LES for turbulence - Filter width =0.1D

48 Flow structures development CLICK ON MOVIE

49 Film thickness Film thickness varies with height and circumferentially, With a radial correlation for the most unstable modes Entrainment in the core flow

50 Film thickness (normalized by initial value) Film thickness could vary as much as 5 times the initial value

51 Coherent/disturbance waves Entrainment in the core flow Disturbance waves

52 Thin-film annular flow (LES/MILES + LS) Flow conditions: - D = m - L = 0.2 m (shorter length for periodicity) - Water and air - V G = 1950 L/m, Re G = 8.09 x V L = 0.5 L/m, Re L = Initial film thickness: h/d = 0.01, then h adjusts itself to the flow to an average of 1-3 x 10-4 Computational parameters & modelling - Periodic domain in flow direction to sustain turbulence - BFC Grid : 937,000 cells, with 12,500 covering cross section - Comp. Time: 763 CPU H on 15 proc. (MPI parallel) local cluster - Level Set - Under-resolved DNS of turbulence; (diffusion effects left to discretization MILES approach)

53 Thin Film: interfacial instabilities

54 Thin Film: transition to turbulence

55 Thin Film: transition to turbulence CLICK ON MOVIE

56 Two-phase flow in vertical pipe (FZD) Bubbly & churn flow experiment of Prasser et al. (2006). TOPFLOW D = 194mm - OpenMP 3D computation: 8h on a PC grid cells - Homogeneous Algebraic Slip Model - Tomiyama lift & drag coeff. correlations - Turbulence: - LES with Smagorinsky model, - V-LES (only results shown) - URANS

57 Churn flow case (TOPFLOW 118) churn flow case. TOPFLOW-128 Click on movie to play

58 Entrainment Modelling: Annular flow

59 Annular Flow (full domain) Jg = 20 m/s, Jl = 1.5 m/s, Domain Spans 1 full wavelength

60 Annular Flow (full domain) Ligament formation, droplet detachment, formation of large disturbance wave clearly visible in these simulations Flow for full domain still developing

61 Annular Flow (full domain) Cross Sectional View of Full Domain Simulation at (a) t = 5.8 ms, (b) t=33.1 ms, (c) t=78.9 ms, (d) t=133.4 ms

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