Two-phase flow is commonly encountered in various engineering systems. Momentum fluctuation in tw... more Two-phase flow is commonly encountered in various engineering systems. Momentum fluctuation in two-phase flow can create undesirable and destructive vibrations. These vibrations are known as flow-induced vibrations, which are a fundamental phenomenon in fluid–structure interactions, and have been the center of this type of research in the past few decades. Flow-induced vibrations due to the multiphase flow are a complex phenomenon and its understanding is still immature. Various accidents related to flow-induced vibrations have been reported in heat exchangers and piping systems and it is very important to develop a deeper understanding of flow-induced vibrations in multiphase flow. The present review article aims to discuss the literature related to flow-induced vibrations, with special focus on factors affecting flow-induced vibrations in internal two-phase flow. Various factors affecting the magnitude and dominant frequency of forces are narrated and the correlations previously d...
Among numerous electronic cooling methods, a vibrating heat sink using sinusoidal wave vibration ... more Among numerous electronic cooling methods, a vibrating heat sink using sinusoidal wave vibration effectively enhances the heat transfer by disturbing the thermal boundary layer. However, sinusoidal wave vibration has reached its limits in enhancing heat transfer. The present study utilizes a new square wave-shaped vibration and numerically investigates the thermal performance of a heat sink subjected to sinusoidal and square waves vibration. It is found that using the square wave vibration is more beneficial to the thermal performance of the heat sink than the sinusoidal wave. The sudden impulsive motion of square wave vibration induces a higher randomness of the airflow profile and recirculation zones than the sinusoidal wave, causing the air flow to impinge directly into the fin surfaces, and further enhances the heat transfer. Furthermore, increasing the frequency and amplitude leads to a higher heat transfer enhancement. Moreover, square wave vibration achieves a 25% increase in...
T-junction is a pipe configuration used to separate two-phase flow. Normally, when slug flow pass... more T-junction is a pipe configuration used to separate two-phase flow. Normally, when slug flow pass through T-junction, a large amount of liquid being drawn into side arm causing high liquid carryover. This liquid furtherly flow into the equipment and causing the platform to trip. The objective of this project was to determine the separation effectiveness of diverging T-junction using CFD simulation. There were five different diverging T-junction configurations tested which were T1 (0.2,1), T2 (0.5,1), T3(0.8,1), T4 (0.27,0.67), and T5 (0.5,0.67). Each of these T-junction have different combination diameter ratio 1 (DR1) and diameter ratio 2 (DR2). The air and water superficial velocity used were 3.2396 m/s and 1.4 m/s respectively meanwhile the temperature and pressure were set at ambient level, t=298K and P=101.325 Pa. The horizontal length of pipe was set at 6m and vertical length pipe was set at 2.5m total. The diameter of the main arm of pipe was 0.074 m. ANSYS FLUENT was used wi...
T-junction is commonly used in distributing two-phase flow in a piping system, especially in oil ... more T-junction is commonly used in distributing two-phase flow in a piping system, especially in oil and gas industries. In offshore Malaysia, T-junction is installed at the production header as a compact separator to tap produced gas from reservoir as fuel gas for power generation. However, the splitting nature of two-phase flow with signficant differential density at the junction is a major challenge. Excessive liquid carryover in T-junction present a serious operational issue because it trips the whole production platform. The primary objective of the present study is to investigate the liquid carryover due to formation of slug, subsequently its separation eciency at different diameter ratio. The analysis was carried out on a model with 0.0254 m (1 inch) diameter horizontal main arm and a vertically upward side arm using Volume of Fluid Method from Fluent 16.1. Three different side to main arm diameter ratio of 1.0, 0.5 and 0.3 were investigated with different gas and liquid supercia...
Erosion-corrosion of elbow configurations has recently been a momentous concern in hydrocarbon pr... more Erosion-corrosion of elbow configurations has recently been a momentous concern in hydrocarbon processing and transportation industries. The carbon steel 90° elbows are susceptible to the erosion-corrosion during the multiphase flow, peculiarly for erosive slug flows. This paper studies the erosion-corrosion performance of 90° elbows at slug flow conditions for impact with 2, 5, and 10 wt.% sand fines concentrations on AISI 1018 carbon steel exploiting quantitative and qualitative analyses. The worn surface analyses were effectuated by using laser confocal and scanning electron microscopy. The experiment was conducted under air and water slug flow containing sand fines of 50 µm average size circulated in the closed flow loop. The results manifest that with the increase of concentration level, the erosion-corrosion magnitude increases remarkably. Sand fines instigate the development of perforation sites in the form of circular, elongated, and coalescence pits at the elbow downstream ...
Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, 2021
Whenever T-junctions are used in chemical processes and petroleum industries for two-phase separa... more Whenever T-junctions are used in chemical processes and petroleum industries for two-phase separation, a maldistribution of phases is observed between outlets of the junction. Currently, the regular T-junctions are utilized in the industry due to which equipment downstream faces high liquid carryovers. Unfortunately, downstream equipment is not capable of handling high liquid carryovers and they trip frequently, consequently. This review manuscript summarizes the effect of different factors that influence phase separation in the T-junction. This article refers to the geometrical parameters, phase superficial velocity flow regimes encounter during the separation process, and different side arm modifications. This article is a contribution to this field as it summarizes and concludes all these factors comprehensively, to give a verdict on ways to improve phase separation. It is also recommended that the effect of side arm modifications or combinations must be explored for further unde...
Temperature fluctuation occurs while mixing of hot and cold fluids in a T-junction due to incompl... more Temperature fluctuation occurs while mixing of hot and cold fluids in a T-junction due to incomplete thermal mixing. This temperature fluctuation can produce thermal fatigue at the weld area of the T-junction. The present study aims to numerically investigate the thermal mixing characteristics of hot and cold fluids in a T-junction. The realizable k-ε turbulence model is used with natural gas as the working fluid. Temperature distribution, mixing quality, and intensity of temperature fluctuation are evaluated and compared along with the mixing outlet. The inlet temperature difference and branch to main pipe flowrate ratio have a direct influence on thermal mixing. The higher temperature difference can reduce the thermal mixing performance. Thermal mixing increases with the increase of branch to main pipe flowrate. The intensity of temperature fluctuation is found within a short distance from the intersecting point of the two inlets. With the increase of distance along with the mixin...
Erosion–corrosion in flow changing devices as a result of sand transportation is a serious concer... more Erosion–corrosion in flow changing devices as a result of sand transportation is a serious concern in the hydrocarbon and mineral processing industry. In this work, the flow accelerated erosion–corrosion mechanism of 90°, 60°, and 30° long radius horizontal–horizontal (H–H) carbon steel elbows with an inner diameter of 50.8 mm were investigated in an experimental closed-flow loop. For these geometrical configurations, erosion–corrosion was elucidated for erosive slug flow regimes and the extent of material degradation is reported in detail. Qualitative techniques such as multilayer paint modeling and microscopic surface imaging were used to scrutinize the flow accelerated erosion–corrosion mechanism. The 3D roughness characterization of the surface indicates that maximum roughness appears in downstream adjacent to the outlet of the 90° elbow. Microscopic surface imaging of eroded elbow surfaces disseminates the presence of corrosion pits on the exit regions of the 90° and 60° elbows...
Journal of Mechanical Engineering and Sciences, 2019
The experimental data for phase separation of the air-water mixture in a T-Junction with the expa... more The experimental data for phase separation of the air-water mixture in a T-Junction with the expander section after the branch arm is presented in this work. The main and run arms of the T-junction are directed along the horizontal plane with the branch arm positioned in the vertical plane. The diameter of the main arm is 74 mm, with diameter ratio(s) of, 0.67, and 0.33 in relation to branch arm. At the inlet section of the T-junction, the flow regimes generated were stratified, stratified wavy and slug flow. At the inlet, the air and water superficial velocities are in the range of 0.25 - 0.140 m/s and 0.14-0.78 m/s respectively. The effect of the expander section after the branch arm, the air superficial velocity USA and water superficial velocity USw on liquid carryover (WL3/WL1)max in branch arm have been studied. Based on the experimental data obtained for T-junction with expander section, complete phase separation of air and water was observed in stratified and stratified wavy...
Erosion-corrosion is an ineluctable flow assurance problem confronted in hydrocarbon transportati... more Erosion-corrosion is an ineluctable flow assurance problem confronted in hydrocarbon transportation and production systems. In this work, the effect of sand fines velocity on the erosion-corrosion behavior of AISI 1018 carbon steel long radius 90° elbows was experimentally and numerically investigated for liquid-solid flow conditions. Experiments were effectuated for sand fines of mean diameter 50 µm circulated in a flow loop with three different velocities (0.5, 1 and 2 m/s). To elucidate the erosion-corrosion mechanism and degradation rate, the material loss analysis, multilayer paint modeling (MPM) and microscopic imaging technique were employed, with computational fluid dynamics (CFD) and discrete phase modeling (DPM) also capacitating to evaluate the erosion distribution. It was perceived that increasing slurry velocity significantly changes the particle-wall impaction mechanism, leading to an increase in material degradation in the elbow bottom section up to 2 times in compari...
Excessive liquid carryover in T-junction due to splitting nature of two-phase flow causes serious... more Excessive liquid carryover in T-junction due to splitting nature of two-phase flow causes serious issues in piping system. A three-dimensional numerical model is employed to investigate two-phase flow split behavior of slug flow in a circular-section regular T-junction with 0.0752 m diameter. The Volume of Fraction method combined with k-ε turbulence model and initial sinusoidal perturbation in ANSYS FLUENT is adopted to characterize the effect of slug flow behavior on the phase separation efficiency. The preliminary result reveals that the simulation work can study slug flow split in great detail and the slug characteristic plays an important role in understanding split behavior.
International Journal of Numerical Methods for Heat & Fluid Flow, 2017
Purpose This research aims to investigate the effects of manipulation of a torpedo’s geometries t... more Purpose This research aims to investigate the effects of manipulation of a torpedo’s geometries to attain higher terminal velocity. The parameters of interest include geometric changes of the original design, as well as sea water properties that reflect water depth in South China Sea. Design/methodology/approach The research make use of computational fluid dynamics (CFD) software, FLUENT, to solve viscous incompressible Navier–Stokes equations with two equations k-epsilon turbulent model. The calculated drag coefficient is subsequently used to calculate the maximum attainable terminal velocity of the torpedo. Findings It was found that the terminal velocity can be improved by sharper tip angle, greater aspect ratio, greater diameter ratio and optimum rear angle at 30°. Sensitivity of drag coefficient toward each of the parameters is established in this paper. Originality/value The paper, in addition to verifying the importance of aspect ratio, has also established the tip angle, dia...
2013 IEEE Student Conference on Research and Developement, 2013
Reservoir simulation software is an important tool in oil and gas industries to predict the multi... more Reservoir simulation software is an important tool in oil and gas industries to predict the multiphase flow of reservoirs. The output from reservoir simulation consists of production history, reservoir pressure, grid block saturation, porosity and permeability change etc. Due to the intrinsic set of uncertainty in reservoir simulation prediction, considerable number of simulation runs to be performed. As reservoir models becoming more complex, the size of the resulting reservoir models become larger and larger. Making hundreds and thousands of simulations require considerable amount of time and sometimes simply impractical. Hence, Well-based Surrogate Reservoir Model (SRM) is a potential candidate to be used as a solution tool to solve this issue. This paper presents a workflow of Well-based SRM that mines the output data from conventional dynamic reservoir simulation. As a part of this system, it is proposed to develop Well-based SRM extraction based on Artificial Neural Network (ANN) to enhance the realization run time. Well-based SRM is used for fast track analysis, decision optimization and has the capability of generating shorter time simulation response in relation to the conventional dynamic reservoir model.
Two-phase flow is commonly encountered in various engineering systems. Momentum fluctuation in tw... more Two-phase flow is commonly encountered in various engineering systems. Momentum fluctuation in two-phase flow can create undesirable and destructive vibrations. These vibrations are known as flow-induced vibrations, which are a fundamental phenomenon in fluid–structure interactions, and have been the center of this type of research in the past few decades. Flow-induced vibrations due to the multiphase flow are a complex phenomenon and its understanding is still immature. Various accidents related to flow-induced vibrations have been reported in heat exchangers and piping systems and it is very important to develop a deeper understanding of flow-induced vibrations in multiphase flow. The present review article aims to discuss the literature related to flow-induced vibrations, with special focus on factors affecting flow-induced vibrations in internal two-phase flow. Various factors affecting the magnitude and dominant frequency of forces are narrated and the correlations previously d...
Among numerous electronic cooling methods, a vibrating heat sink using sinusoidal wave vibration ... more Among numerous electronic cooling methods, a vibrating heat sink using sinusoidal wave vibration effectively enhances the heat transfer by disturbing the thermal boundary layer. However, sinusoidal wave vibration has reached its limits in enhancing heat transfer. The present study utilizes a new square wave-shaped vibration and numerically investigates the thermal performance of a heat sink subjected to sinusoidal and square waves vibration. It is found that using the square wave vibration is more beneficial to the thermal performance of the heat sink than the sinusoidal wave. The sudden impulsive motion of square wave vibration induces a higher randomness of the airflow profile and recirculation zones than the sinusoidal wave, causing the air flow to impinge directly into the fin surfaces, and further enhances the heat transfer. Furthermore, increasing the frequency and amplitude leads to a higher heat transfer enhancement. Moreover, square wave vibration achieves a 25% increase in...
T-junction is a pipe configuration used to separate two-phase flow. Normally, when slug flow pass... more T-junction is a pipe configuration used to separate two-phase flow. Normally, when slug flow pass through T-junction, a large amount of liquid being drawn into side arm causing high liquid carryover. This liquid furtherly flow into the equipment and causing the platform to trip. The objective of this project was to determine the separation effectiveness of diverging T-junction using CFD simulation. There were five different diverging T-junction configurations tested which were T1 (0.2,1), T2 (0.5,1), T3(0.8,1), T4 (0.27,0.67), and T5 (0.5,0.67). Each of these T-junction have different combination diameter ratio 1 (DR1) and diameter ratio 2 (DR2). The air and water superficial velocity used were 3.2396 m/s and 1.4 m/s respectively meanwhile the temperature and pressure were set at ambient level, t=298K and P=101.325 Pa. The horizontal length of pipe was set at 6m and vertical length pipe was set at 2.5m total. The diameter of the main arm of pipe was 0.074 m. ANSYS FLUENT was used wi...
T-junction is commonly used in distributing two-phase flow in a piping system, especially in oil ... more T-junction is commonly used in distributing two-phase flow in a piping system, especially in oil and gas industries. In offshore Malaysia, T-junction is installed at the production header as a compact separator to tap produced gas from reservoir as fuel gas for power generation. However, the splitting nature of two-phase flow with signficant differential density at the junction is a major challenge. Excessive liquid carryover in T-junction present a serious operational issue because it trips the whole production platform. The primary objective of the present study is to investigate the liquid carryover due to formation of slug, subsequently its separation eciency at different diameter ratio. The analysis was carried out on a model with 0.0254 m (1 inch) diameter horizontal main arm and a vertically upward side arm using Volume of Fluid Method from Fluent 16.1. Three different side to main arm diameter ratio of 1.0, 0.5 and 0.3 were investigated with different gas and liquid supercia...
Erosion-corrosion of elbow configurations has recently been a momentous concern in hydrocarbon pr... more Erosion-corrosion of elbow configurations has recently been a momentous concern in hydrocarbon processing and transportation industries. The carbon steel 90° elbows are susceptible to the erosion-corrosion during the multiphase flow, peculiarly for erosive slug flows. This paper studies the erosion-corrosion performance of 90° elbows at slug flow conditions for impact with 2, 5, and 10 wt.% sand fines concentrations on AISI 1018 carbon steel exploiting quantitative and qualitative analyses. The worn surface analyses were effectuated by using laser confocal and scanning electron microscopy. The experiment was conducted under air and water slug flow containing sand fines of 50 µm average size circulated in the closed flow loop. The results manifest that with the increase of concentration level, the erosion-corrosion magnitude increases remarkably. Sand fines instigate the development of perforation sites in the form of circular, elongated, and coalescence pits at the elbow downstream ...
Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, 2021
Whenever T-junctions are used in chemical processes and petroleum industries for two-phase separa... more Whenever T-junctions are used in chemical processes and petroleum industries for two-phase separation, a maldistribution of phases is observed between outlets of the junction. Currently, the regular T-junctions are utilized in the industry due to which equipment downstream faces high liquid carryovers. Unfortunately, downstream equipment is not capable of handling high liquid carryovers and they trip frequently, consequently. This review manuscript summarizes the effect of different factors that influence phase separation in the T-junction. This article refers to the geometrical parameters, phase superficial velocity flow regimes encounter during the separation process, and different side arm modifications. This article is a contribution to this field as it summarizes and concludes all these factors comprehensively, to give a verdict on ways to improve phase separation. It is also recommended that the effect of side arm modifications or combinations must be explored for further unde...
Temperature fluctuation occurs while mixing of hot and cold fluids in a T-junction due to incompl... more Temperature fluctuation occurs while mixing of hot and cold fluids in a T-junction due to incomplete thermal mixing. This temperature fluctuation can produce thermal fatigue at the weld area of the T-junction. The present study aims to numerically investigate the thermal mixing characteristics of hot and cold fluids in a T-junction. The realizable k-ε turbulence model is used with natural gas as the working fluid. Temperature distribution, mixing quality, and intensity of temperature fluctuation are evaluated and compared along with the mixing outlet. The inlet temperature difference and branch to main pipe flowrate ratio have a direct influence on thermal mixing. The higher temperature difference can reduce the thermal mixing performance. Thermal mixing increases with the increase of branch to main pipe flowrate. The intensity of temperature fluctuation is found within a short distance from the intersecting point of the two inlets. With the increase of distance along with the mixin...
Erosion–corrosion in flow changing devices as a result of sand transportation is a serious concer... more Erosion–corrosion in flow changing devices as a result of sand transportation is a serious concern in the hydrocarbon and mineral processing industry. In this work, the flow accelerated erosion–corrosion mechanism of 90°, 60°, and 30° long radius horizontal–horizontal (H–H) carbon steel elbows with an inner diameter of 50.8 mm were investigated in an experimental closed-flow loop. For these geometrical configurations, erosion–corrosion was elucidated for erosive slug flow regimes and the extent of material degradation is reported in detail. Qualitative techniques such as multilayer paint modeling and microscopic surface imaging were used to scrutinize the flow accelerated erosion–corrosion mechanism. The 3D roughness characterization of the surface indicates that maximum roughness appears in downstream adjacent to the outlet of the 90° elbow. Microscopic surface imaging of eroded elbow surfaces disseminates the presence of corrosion pits on the exit regions of the 90° and 60° elbows...
Journal of Mechanical Engineering and Sciences, 2019
The experimental data for phase separation of the air-water mixture in a T-Junction with the expa... more The experimental data for phase separation of the air-water mixture in a T-Junction with the expander section after the branch arm is presented in this work. The main and run arms of the T-junction are directed along the horizontal plane with the branch arm positioned in the vertical plane. The diameter of the main arm is 74 mm, with diameter ratio(s) of, 0.67, and 0.33 in relation to branch arm. At the inlet section of the T-junction, the flow regimes generated were stratified, stratified wavy and slug flow. At the inlet, the air and water superficial velocities are in the range of 0.25 - 0.140 m/s and 0.14-0.78 m/s respectively. The effect of the expander section after the branch arm, the air superficial velocity USA and water superficial velocity USw on liquid carryover (WL3/WL1)max in branch arm have been studied. Based on the experimental data obtained for T-junction with expander section, complete phase separation of air and water was observed in stratified and stratified wavy...
Erosion-corrosion is an ineluctable flow assurance problem confronted in hydrocarbon transportati... more Erosion-corrosion is an ineluctable flow assurance problem confronted in hydrocarbon transportation and production systems. In this work, the effect of sand fines velocity on the erosion-corrosion behavior of AISI 1018 carbon steel long radius 90° elbows was experimentally and numerically investigated for liquid-solid flow conditions. Experiments were effectuated for sand fines of mean diameter 50 µm circulated in a flow loop with three different velocities (0.5, 1 and 2 m/s). To elucidate the erosion-corrosion mechanism and degradation rate, the material loss analysis, multilayer paint modeling (MPM) and microscopic imaging technique were employed, with computational fluid dynamics (CFD) and discrete phase modeling (DPM) also capacitating to evaluate the erosion distribution. It was perceived that increasing slurry velocity significantly changes the particle-wall impaction mechanism, leading to an increase in material degradation in the elbow bottom section up to 2 times in compari...
Excessive liquid carryover in T-junction due to splitting nature of two-phase flow causes serious... more Excessive liquid carryover in T-junction due to splitting nature of two-phase flow causes serious issues in piping system. A three-dimensional numerical model is employed to investigate two-phase flow split behavior of slug flow in a circular-section regular T-junction with 0.0752 m diameter. The Volume of Fraction method combined with k-ε turbulence model and initial sinusoidal perturbation in ANSYS FLUENT is adopted to characterize the effect of slug flow behavior on the phase separation efficiency. The preliminary result reveals that the simulation work can study slug flow split in great detail and the slug characteristic plays an important role in understanding split behavior.
International Journal of Numerical Methods for Heat & Fluid Flow, 2017
Purpose This research aims to investigate the effects of manipulation of a torpedo’s geometries t... more Purpose This research aims to investigate the effects of manipulation of a torpedo’s geometries to attain higher terminal velocity. The parameters of interest include geometric changes of the original design, as well as sea water properties that reflect water depth in South China Sea. Design/methodology/approach The research make use of computational fluid dynamics (CFD) software, FLUENT, to solve viscous incompressible Navier–Stokes equations with two equations k-epsilon turbulent model. The calculated drag coefficient is subsequently used to calculate the maximum attainable terminal velocity of the torpedo. Findings It was found that the terminal velocity can be improved by sharper tip angle, greater aspect ratio, greater diameter ratio and optimum rear angle at 30°. Sensitivity of drag coefficient toward each of the parameters is established in this paper. Originality/value The paper, in addition to verifying the importance of aspect ratio, has also established the tip angle, dia...
2013 IEEE Student Conference on Research and Developement, 2013
Reservoir simulation software is an important tool in oil and gas industries to predict the multi... more Reservoir simulation software is an important tool in oil and gas industries to predict the multiphase flow of reservoirs. The output from reservoir simulation consists of production history, reservoir pressure, grid block saturation, porosity and permeability change etc. Due to the intrinsic set of uncertainty in reservoir simulation prediction, considerable number of simulation runs to be performed. As reservoir models becoming more complex, the size of the resulting reservoir models become larger and larger. Making hundreds and thousands of simulations require considerable amount of time and sometimes simply impractical. Hence, Well-based Surrogate Reservoir Model (SRM) is a potential candidate to be used as a solution tool to solve this issue. This paper presents a workflow of Well-based SRM that mines the output data from conventional dynamic reservoir simulation. As a part of this system, it is proposed to develop Well-based SRM extraction based on Artificial Neural Network (ANN) to enhance the realization run time. Well-based SRM is used for fast track analysis, decision optimization and has the capability of generating shorter time simulation response in relation to the conventional dynamic reservoir model.
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Papers by William Pao