ORIFICE PLATE
CFD Model Assumptions
- Natural gas was assumed to be 100% methane (CH4) at constant flow rate Q=37 MMSCFD (8.212kg/s)
- Fluid flow was assumed to be incompressible and isothermal
· low pressure drop compared to absolute pressure
· Mach number is below 0.1
· Heat transfer was neglected
- Transport properties for CH4 computed at P=1590 psig (1604.7 psia) and T= 164oF=346.48 K
· density =66.06 kg/m3 (BWRS Lee-Starling equation of states)
· viscosity = 0.015cP=0.000015kg/ms (Cheng-Lee-Starling model)
- Steady (time-averaged) simulations of turbulent flow field using realizable k-epsilon turbulence model
· Re=1.25x106 (fully turbulent)
· Turbulent boundary layer modeled using non-equilibrium wall function with a prescribed surface roughness of 100 microns
Prosedur CFD
- Atur domain
- Dim; p=25*0.5588=13.97m; t=0.5588m; l=bawaan
- Jumlah Cell (disesuaikan dengan perbandingan dimensi panjang dan tinggi (25:1); x=250 ;y=12 (10+2[dinding atas & bawah])
- Atur Cell (AC)
- Inlet
x=1
1
y=2
11
- Outlet
x=250
250
y=2
11
- Orifice (ww1)
x=51
51
y=8
11
x=51
51
y=2
5
- Dinding (ww1)
x=1
250
y=1
1
x=1
250
y=12
12
- Bangun Grid (bg) searah x karena perubahan dimensi searah x
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Inisiasi segmen
Segmen 1
50
Segmen 2
(3.206/2.794)*50=57
Segmen 3
248-50-57=141
Modif segmen (ms) tujuan untuk memperapat grid pada segemen yang akan dianalisa
Segmen
2
Faktor pemberat awal
2.1
Faktor pemberat akhir
0
- Mahir
Gb
-9.81
Lainnya enter
Density acuan ditetapkan user
Y
Ref density
66.06
- Konstanta Fiskal (kf)
Density 66.06 kg/m3
Viscosity 1.5e-5
- Atur model (am)
PP
Y
Lainnya enter
Am
Tu
k-epsilon
Y
Lainnya enter
- Kondisi Sempadan
Inlet
Ku=0.57 m/s
Temp
346.483
Ww1
Temp
300
- Save
TFC
Mhscfds2-9/orifice
- Iter sampai konvergen
- Hasil CFD SOF
Berdasarkan analisa CFD SOF, ketika fluida masuk orrife, kecepatan tinggi sehingga pressure menjadi rendah.
Alhamdulillah-fin
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