G. Lackner et al., NUMERICAL-SIMULATION OF THE GAS-LIQUID FLOW IN A ROTARY GAS SEPARATOR, Journal of energy resources technology, 120(1), 1998, pp. 41-48
The presence of free gas at the pump intake adversely affects the perf
ormance of an electrical submersible pump (ESP) system, often resultin
g in low efficiency and causing operational problems. One method of re
ducing the amount of free gas that the pump has to process is to insta
ll a rotary gas separator. The gas-liquid flow associated with the dow
nhole installation of a rotary separator has been investigated to addr
ess its overall phase segregation performance. A mathematical model wa
s developed to investigate factors contributing to gas-liquid separati
on and to determine the efficiency of the separator. The drift-flux ap
proach was used to formulate this complex two-phase flow problem. The
turbulent diffusivity was modeled by a two-layer mixing-length model a
nd the relative velocity between phases was formulated based on publis
hed correlations for flows with similar characteristics. The well-know
n numerical procedure of Patankar-Spalding for single-phase flow compu
tations was extended to this two-phase flow situation. Special discret
ization techniques were developed to obtain consistent results. Specia
l underrelaxation procedures were also developed to keep the gas void
fraction in the interval [0, 1]. Predicted mixture velocity vectors an
d gas void fraction distribution for the two-phase flow inside the cen
trifuge are presented. The model's predictions are compared to data ga
thered on a field scale experimental facility to support its invaluabl
e capabilities as a design tool for ESP installations.