DRAG COEFFICIENT AND VOID FRACTION IN LAMINAR GAS-LIQUID CROSS FLOW AROUND A CYLINDRICAL PROBE

A two-phase flow around a body has scarcely been studied until now, although this flow is used in many industrial components. Importance of studying these flows is that these two-phase cross flows play a significant role in efficiency and reliability of many industrial apparatuses. In this paper main flow equations of an air-water two-phase flow developed in order to carry out the drag coefficient, vortex shedding behind cylinder, void fraction and pressure coefficient distribution around different diameters of cylindrical cross-section. Our numerical analyses were performed by a designed and written CFD package which is based on Eulerian-Eulerian approach. Diameters of cylinder which have been studied in this paper are 5-15 mm (step 5 mm). Two-phase flow over these different cross sections, also, considered in different Reynolds numbers and volume fractions of flow. Considered volume fractions for each Reynolds number and each diameter are: 0.02, 0.05, 0.1, 0.15 and 0.2. Also, considered Reynolds numbers in analyses of one particular diameter and volume fraction are: 500, 1000, 2000, 2500 and 3000. Free stream void fraction and bubble size were considered, too. Drag coefficient is closely relates to the bubble motion. Since this mechanism varies over time, we used time-average value of drag coefficient. The results showed that drag coefficient is strongly depended of Reynolds number.

کلیدواژه ها:

Two-phase flow ، Drag coefficient ، Reynolds number ، Volume fraction