Experimental study on the hydrodynamic behavior of gas-liquid air-water two-phase flow near the transition to slug flow in horizontal pipes

Onset of intermittent flow: Visualization of flow structures

“…It is noted that an increase in diameter required a higher liquid superficial velocity for the initiation of liquid slugs. The fact that the onset of slug flow in our study occurred at a lower liquid superficial velocity compared to the studies of Thaker and Banerjee (25 mm) [10] and Deendarlianto et al (26 mm) [12], which were carried out on smaller diameters, is due to the type of inlet mixer. For the present study, a T-mixer was used, which generated greater disturbances, precipitating the formation of slugs than the mixer used in the above-mentioned works.…”

“…The authors, in their experiment on a 26 mm ID pipe, reported the occurrence of WG at low gas superficial velocities; WC at high gas superficial velocities and DW at high liquid superficial velocities with one of the two mechanisms WG or WC. An increase in diameter caused a shift in the stratified/slug and pseudo-slug/slug flows transitions as reported by Deendarlianto et al [12]. In addition, the authors pointed out that WG is responsible for the transition from stratified to plug and Less Aerated Slug (LAS) flows, whereas WC induced a transition from stratified wavy or roll waves to Highly Aerated Slug (HAS) flows, through pseudo-slug.…”

“…With V SG , V SL , q G , q L , D and g are the gas superficial velocity, liquid superficial velocity, gas density, liquid density, pipe's diameter and gravity, respectively. Nevertheless, discrepancies remain between most of the above-mentioned studies and the lack of a complete model for the onset of intermittent flow prediction exist [12]. Experimental observations as well as measurements of some parameters are still necessary steps in the understanding of the transition from stratified to intermittent flow.…”

“…The interface of liquid slugs and gas pockets can exhibit various shapes, and liquid slugs can display different levels of aerations, resulting in several types of intermittent flows, called sub-regimes. Intermittent flows have been classified in three sub-regimes: Plug flow, Less Aerated Slug flow (LAS flow) and Highly Aerated Slug flow (HAS flow) [10][11][12][13]. The hydrodynamic behavior of each sub-regime is different [11,13] and requires to be modeled separately.…”

The Visualization Study on the Slug Flow Mechanisms of the Air-Water Two-Phase in a 50 mm Horizontal Pipe

“…Akan tetapi kehadiran aliran slug akan berakibat buruk pada kegiatan operasional dan keamanan sistem perpipaan. Oleh karena itu aliran slug banyak dihindari oleh desainer dan operator pada sistem perpipaan [1][2][3][4] Pola aliran slug merupakan pola yang tidak stabil di mana tumbuh dan leyapnya sangatlah fluktuatif [5]. Pada aliran slug terjadi perubahan tekanan secara mendadak dan dapat merusak sistem perpipaan.…”