Search

Slug flow is the most prevalent problem of two-phase fluid transportation in the petroleum industries. Here, large amplitude waves lead to the pipe blockage that possible to cause the damage of the mechanical structure. The experimental investigation of gas-liquid slug two-phase flow in a horizontal pipe was carried out to investigate the initiation and flow development mechanisms. Air and water were used as the working fluids. The inner pipe diameter was 26 mm. In the present experimental study, the slug initiation mechanisms were explained by visual observation and pressure fluctuations. Moreover, the initiation frequency of slug flow and the evolution of passing slug frequency along the pipeline were also observed by using two high video cameras. As a result, several basic mechanisms of slug flow initiation in a horizontal pipe were clarified. Those were the wave coalescences, the wave growth mechanism, and the large disturbance waves. A flow initiation map was proposed to address those mechanisms. Here, the slug initiation frequency and the passing slug frequency were obtained in relation to the pipe length position. The static pressure measurement was also used to verify the image processing results on the characteristics of slug initiation mechanisms. The obtained qualitative and quantitative results from the investigation can be used to evaluate the recent available models.

The slug flow phenomena are often encountered in various industrial applications such as petroleum, process, and power plant. The presence of slug flow should be avoided as it causes structural damage due to resonance, corrosion and pipes blast. From the view point of multiphase flow, the understanding of the slug initiation mechanism is very important in pipeline design. This research is conducted using horizontal transparent acrylic pipes with diameters of 50 mm with a variation on the superficial velocity of water between 0,1 m/s and 0,77 m/s and superficial velocity of air between 0,31 m/s and 6,2 m/s. In the present experimental study, the slug initiation mechanisms was explained by visual observation by using high speed video cameras. As the results, the slug flow initiation mechanism were clarified. Furthermore, the proposed of flow initiation map was introduced.

In the operation of horizontal two-phase flow system, stratified flow should be maintained since it provides good key operational factors and pipe construction safety. Recently, the investigations of stratified flow have widely covered various aspects of the flow, such as the liquid hold-up. An image processing technique devotes numerous advantages related to the abilities of non-intrusive measurement and quantitative visualization. The aim of the present work was to implement the image processing technique to study the characteristics of the stratified flow. Here, the observations were conducted in a transparent horizontal pipe with inner diameter of 50 mm. Air and water were used as the working fluid. The liquid superficial velocity (J L ) was between 0.005 m/s to 0.05 m/s while the gas superficial velocity (J G ) was between 0.94 m/s to 6.00 m/s. The data was processed by using the image processing algorithms that have been developed in the previous study. As a result, qualitative and quantitative identifications of each stratified flow patterns (smooth, ripple, and roll) have been carried out by using an image processing technique. The effects of gas and liquid superficial velocities to stratified flow behaviors were also obtained. Moreover, this study proved that the developed algorithm has been successfully implemented in the present stratified flow case. Furthermore, it can be a promising method to be used in other cases of stratified flow and validation of the available CFD simulation models on stratified flow in horizontal pipes.

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.