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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 1 CFD Modelling of the Flow Inside an LC Refiner Dariusz Asendrych, Grzegorz Kondora Częstochowa Univ. of Technology, Poland A joint meeting COST Action FP1005 Fibre suspension flow modelling - a key for innovation & competitiveness in the pulp & paper industry ERCOFTAC SIG 43 Fibre suspension flows
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 2 Introduction / Motivation Numerical model Simplified / full geometry Boundary conditions Governing equations Results Simplified geometry - Diverging grooves Full geometry - General flow pattern Summary / Perspectives Outline
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 3 plate disc refiner Geometry – assumptions simplified neglected housing axisymmetric outlet (instead of point outlet) neglected axial part of inlet, radial inlet applied periodicity of discs geometry - single- segment (30 degrees of angular extent - 1/12) full 12 segments housing single-pipe outlet typical refiner filling LC refiner
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 4 simplified filling inlet - VELOCITY INLET outlet - PRESSURE OUTLET PERIODIC B.C. INTERFACE for sliding meshes geometry and mesh - GAMBIT mesh: 6 / 24 mln cells FLUENT 6.3 / 13 Boundary conditions
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 5 pulp suspension treated as a single-phase continuum (N-S, continuity) flow character assumed to be laminar (confirmed by simulation results) pulp modelled as either Newtonian or non-Newtonian fluid fibre-fibre and fibre-wall interactions are neglected - main goal was to analyze the LC refining hydraulics or Governing equations where - rate of deformation tensor
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 6 softwood pulp, C m = 4%, fibre lenght = 1400 μm, diameter = 26 μm ln(l/d) = 3,986ln(μ r ) = 5,91 μ r = 370 μ pulp = μ r · μ water = 370 · 0,001003 = 0,371 Pa ·s Newtonian fluid - constant apparent viscosity Pulp material properties source:Radoslavova, Silvy, Roux, 1996,,TAPPI Papermakers Conf., Philadelphia
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 7 reverse flows in stator disc enhanced internal circulation General flow pattern
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 8 α div = 0.0 deg α div = 0.25 deg α div = 0.50 deg Diverging grooves
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 9 intensification of reverse flow Diverging grooves
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 10 Diverging grooves
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 11 mass flux exiting stator grows power consumption decreases Diverging grooves
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 12 Full refiner simulation
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 13 housing includedhousing included pipe outletpipe outlet 12 segments12 segments collector outlet pipe inlet outlet Full refiner geometry model
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 14 Velocity magnitude rotor stator
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 15 Pressure distribution p [bar] 7 6 5 4 3 2 1 0 rotor stator
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 16 Pressure distribution 5432154321 p [bar] r* [-] 5432154321 p [bar] r* 0 1
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 17 Pressure distribution p [bar] 7 6 5 4 3 2 1 0 gap
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 18 LC refiner flow model - Fox et al. Fox, T.S., Brodkey, R.S. Nissan, A.H., 1979, TAPPI J., 62 (3)
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 19 Pressure distribution - CFD vs Fox et al. 01234567[bar] exit region
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 20 Mass flux at filling outlet
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 21 Mass flux at filling outlet full refiner single-segment refiner 2 1 0 -2
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 22 Flow reversals in stator full refiner
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 23 Simplified geometry model qualitative agreement with experimental observation - adequate numerical model divergent grooves: modify pressure distribution and enhance flow reversals no energy penalty - improved flow quality Summary / Perspectives Full geometry model circulation / exit regions - analogy to Fox et al. existence of the backflows in the stator mass flow rate distributions stongly non-uniform and rotor position dependent General no fibres included... CFD can really help - useful tool in process optimisation time consuming simulations ongoing simulations / data processing for varying conditions
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 24 Thank You for Your Attention
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 25 Re is low enough to justify the assumption about laminar flow character gap groove Reynolds number - Laminar vs Turbulent
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 26 Investigated parameters: succesive ratio interval count at the cross-section interval count along the groove Grid tests
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 27 simulation literature velocity vectors axial velocity [Lumiainen] - LDA [Fox et al.] refiner grooves occupied by spiral vortices tertiary flows (momentum exchange between discs) good qualitative agreement CFD vs experiment
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 28 source [Ventura et al.] II - 2 nd invariant o D D - deformation rate tensor non-Newtonian pulp model refining regime istan Pulp material properties
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CFD Modelling of the Flow Inside an LC Refiner COST FP1005 / SIG 43 meeting, 24-26.X.2012, Trondheim 29 Solution monitoring progressing solution (time step No) mass flux at selected groove outlet
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