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In the present work, the hjgh viscous oil-water multiphase flows have been simulated using the Interfacial Area Density (AIAD) model, while the turbulence model was performed using the SST k-ω. The oil (Uso) and water (Usw) superficial velocities were set at 0.06 - 0.12 m/s and 0.23 - I m/s, respectively. The computational domain was adjusted on a horizontal pipe with 26mm in diameter and 1000mm in length for the primary pipe, while the oil and water inlets diameter were set to 12mm. A comparison between the volume of fluid (VOF) model and previous experimental was carried out. A comparison with experimental data showed relatively good agreement, both qualitative and quantitative. The AIAD model exhibited a better simulation result than the VOF model, whereby wavy and droplet were clearly revealed. The flow characteristics were obtained with satisfactory predictions in different flow regimes and the quantitative results of oil volume fraction were also investigated. Moreover, the numerical simulation appeared to be a reliable tool for predicting oil-water flow patterns on high viscous oil-water flow. These results show that the AIAD model run on commercial Fluent was able to investigate the practical case of oil-water flow. [ABSTRACT FROM AUTHOR]

In the present day, CO2 emission has become a significant problem that needs to be resolved. One of the alternative solutions to decrease the CO2 emission is recycling CO2 as flue gas in the combustion chamber. Then, the burning process with CO2 enrichment needs to be understood. Therefore, a numerical study on laminar burning velocity (SL) characteristics of CH4/O2 with CO2 enrichment on oxidizer was conducted using CHEMKIN package GRI-Mech 3.0 chemical kinetic mechanisms and detailed transport properties. As a result of the numerical study can explain the effect of CO2 enrichment on CH4 flame clearly. In detail, the results show that the SL of the CH4/O2/CO2 mixture was decreased as CO2 content increased. Next, CO2 directly participates in the combustion process and contributes to the value of laminar burning velocity. By comparing the SL of CH4/O2/N2, CH4/O2/CO2, and CH4/O2/F-CO2, CO2 dilution on oxidizer mainly contributed by thermal-diffusion rather than chemically. Besides the decrease of SL due to CO2 dilution, the intermediate product (O, OH, CO, CH) will decrease as the CO2 dilution content increases. Finally, these intermediate species contribute positively to SL. [ABSTRACT FROM AUTHOR]

The Liquid hold-up and the Interfacial Friction Factor on the Air-Water Stratified Two-Phase Flow in a Horizontal Pipe have been experimentally investigated using superficial gas and liquid velocity of 4 - 16 m/s and 0.02 to 0.1 m/s, respectively. The stratified flow is observed on the horizontal acrylic pipe with 26 mm inner diameter and 9 m length. This present work has utilized the various methods of observation: visual observation through high speed video camera, hold up measurement by using CECM, and pressure gradient analysis which is gathered from the Validyne pressure transducer. The pressure gradient and liquid hold-up signal are sent through amplifier than converted into digital signal by Analog to Digital Converter (ADC). As a result, the characteristics of stratified flow is successfully revealed. Furthermore, a new correlation for hold-up which is based on the gas and liquid superficial velocity, and Froude number is proposed. The R2 which reaches 0.971 and the small value of error band (around 30 %) shows that the proposed correlation produce a good performance. Similarly, a new correlation for interfacial friction factor is also proposed which is arranged as a function of liquid hold-up, gas, and liquid Reynolds number. It produces a satisfying performance which is proven by the high value of R2, 0.999. Moreover, the error band between the proposed correlation and the experimental data is quite small, around 5 % on most of all data. [ABSTRACT FROM AUTHOR]

The two-phase flow application was commonly found in industrial processes, such as oil and gas production in wells, gas and oil pipelines, etc. The characteristic of two-phase flow had various aspects depending on its interfacial behaviour. The interfacial structures of air-water two-phase flow in a horizontal pipe were experimentally investigated by using visualization method with high speed camera. The experiments were conducted in a horizontal two-phase flow facility, total length 10 m pipe made from acrylic with 26 mm ID. To obtain the flow pattern, a total of 132 flow condition were observed. The superficial gas and liquid velocities were set to 0.31 m/s -- 20 m/s and 0.016 m/s -- 0.77 m/s, respectively. High Speed Camera observation successfully characterized and demonstrated two-phase flow regime in a horizontal pipe. Its also developed flow regime maps. Air-water two-phase flow is characterized by bubble breakup and coalescence in the transition from plug to slug flow. Interfacial instabilities form in stratified to wavy flow, then small waves, larger waves and the droplet entrainment in transition to annular flow. High amplitude wave was required to form the slug flow. This flow pattern maps is a two-phase flow regime transition including stratified flow, plug flow, slug flow, annular flow and sub-regime of each patterns. The influence of superficial velocity of air and water has a significant effect on the flow patterns and sub-regime types. [ABSTRACT FROM AUTHOR]

The aim of this research is to investigate the characteristics of the sub regime of slug flow in horizontal pipe. Here, a 16 mm inner diameter horizontal pipe is utilized in order to observe the specific behavior of each flow pattern. The air and water superficial velocity are 0.7 - 8 m/s and 0.2 m/s - 1.13 m/s, respectively. To obtain thorough insight through visualization, a high speed video camera is installed on the area 190 D where the flow is fully developed. A pair of CECM sensor is also placed to gather the quantitative data from the liquid slug hold up. Furthermore, the pressure characteristics of each sub regime flow pattern are recorded by using pressure transducer. As a result, the present study has been able to provide a comprehensive data of the slug flow sub regime. Broadly, there are four observed sub regime on the slug flow. Slug and plug flow is characterized by the presence of plug flow intermittently. The less aerated slug and highly aerated slug can be distinguished by the degree of aeration which can be verified by liquid hold up measurement. While the slug and wavy flow contains wavy interface on the stratified layer. The analysis of each flow pattern is followed by the propose of a slug flow sub regime flow pattern map which can be a reference for conducting further study or fulfilling industrial need [ABSTRACT FROM AUTHOR]

Slug is one of the most avoided flows in the piping system network. The high pressure fluctuations can cause damage to the pipes. Therefore, prevention of the slug flow is very important. To understand the phenomenon, an experimental study to investigate the pattern of stratified to slug flow transition has been examined. The present work was conducted on a 26 mm diameter acrylic horizontal pipe with the length of 10 m. Air and water are used as working fluids. Visual image capture is done using Phantom Miro M310 High speed camera on L/D 180-210 from inlet. As a supporting visual observation result, CECM method is also used to measure liquid holdup of fluid flow. The onset of slugging mechanism due to change of both gas and liquid superficial velocity will be discussed. As a result, it is found that the slug formation from stratified flow is at least divided into two basic mechanisms. At low gas velocity, the slug stability condition is created by wave growth mechanism. The increase of JG resulted in the increase of aeration and the of the liquid slug length. When the gas velocity is above 3 m/s, wave coalescence and large disturbance waves initiated the onset of slugging. The Increase of JL on the high JG makes the roll waves higher to create a pseudo slug. In addition, it is found that the formation of high aeration slug is seen at JL = 0.3 m/s when JG is maintained at 3.77 m/s. [ABSTRACT FROM AUTHOR]

The co-current air-water two-phase stratified flow is desired to occur in the application of pipelines system, such as natural gas gathering, long distance pipelines, and transmission pipelines, because this flow characteristics offers some advantages related to the safety factor of operational condition. The characteristics of pressure drop in stratified flow is considered as one of an important factor in the capital and operation costs for the simultaneous transportation of gas and liquid in various industries. The main objective of this study is to examine the effect of gas and liquid superficial velocities, and pipes diameter on the characteristics of pressure drop air-water two-phase stratified flow. Experiment has been conducted in 26 and 16 mm i.d. acrylic horizontal pipe with length 9.5 m. Air-water flow was recorded 190 D from the inlet using high speed video camera, and pressure difference was measured between 180 D and 210 D from the inlet using validyne pressure transducer. The common parameters such as visualization, pressure gradient signal in time series, probability density function (PDF), and mean of pressure gradient was analyzed. As a result the effect of gas and liquid superficial velocity, and pipes diameter on the characteristics of pressure gradient can be understood. [ABSTRACT FROM AUTHOR]

Slug flow is a part of intermittent flow which is avoided in industrial application because of its irregularity and high pressure fluctuation. Those characteristics cause some problems such as internal corrosion and the damage of the pipeline construction. In order to understand the slug characteristics, some of the measurement techniques can be applied such as wire-mesh sensors, CECM, and high speed camera. The present study was aimed to determine slug characteristics by using image processing techniques. Experiment has been carried out in 26 mm i.d. acrylic horizontal pipe with 9 m long. Air-water flow was recorded 5 m from the air-water mixer using high speed video camera. Each of image sequence was processed using MATLAB. There are some steps including image complement, background subtraction, and image filtering that used in this algorithm to produce binary images. Special treatments also were applied to reduce the disturbance effect of dispersed bubble around the bubble. Furthermore, binary images were used to describe bubble contour and calculate slug parameter such as gas slug length, gas slug velocity, and slug frequency. As a result the effect of superficial gas velocity and superficial liquid velocity on the fundamental parameters can be understood. After comparing the results to the previous experimental results, the image processing techniques is a useful and potential technique to explain the slug characteristics. [ABSTRACT FROM AUTHOR]

Due to the importance of the two-phase flow researches for the industrial safety analysis, many researchers developed various methods and techniques to study the two-phase flow phenomena on the industrial cases, such as in the chemical, petroleum and nuclear industries cases. One of the developing methods and techniques is image processing technique. This technique is widely used in the two-phase flow researches due to the non-intrusive capability to process a lot of visualization data which are contain many complexities. Moreover, this technique allows to capture direct-visual information data of the flow which are difficult to be captured by other methods and techniques. The main objective of this paper is to present an improved algorithm of image processing technique from the preceding algorithm for the stratified flow cases. The present algorithm can measure the film thickness (hL) of stratified flow as well as the geometrical properties of the interfacial waves with lower processing time and random-access memory (RAM) usage than the preceding algorithm. Also, the measurement results are aimed to develop a high quality database of stratified flow which is scanty. In the present work, the measurement results had a satisfactory agreement with the previous works. [ABSTRACT FROM AUTHOR]

The interfacial wave characteristics of stratified air-water two-phase flow in a horizontal pipe were experimentally investigated by using the flush-mounted constant electric current method (CECM) sensors. The experiments were conducted in a horizontal two-phase flow loop 9.5 m long (L) consisting of transparent acrylic pipe of 26 mm i.d. (D). To obtain the stratified flow pattern, the superficial gas and liquid velocities were set to 1.02 - 3.77 m/s and 0.016 - 0.92 m/s, respectively. Several interfacial wave patterns as described by several investigators were identified. The common parameters such as liquid hold-up, probability distribution function, wave velocity and wave frequency were investigated as the function of the liquid and gas flow rates. The interfacial curvature was calculated on the basis of the liquid hold-up data from the CECM sensors and the liquid film thickness data from the image processing technique in the previous work. As a result, it was found that the mean liquid hold-up decreases with the increase of the superficial gas velocity. In the same sub flow pattern, the wave velocity increases as the superficial gas velocity increases. On the other hand, in the two-dimensional wave region, the dominant frequency decreases with the increase of the superficial liquid velocity. [ABSTRACT FROM AUTHOR]