رسائل ماجيستير
English
2015
Investigation of Flow and Erosion Characteristics Through a Set of Restricting Orifices
Hassan Badr, عراواى عبدالرازق أدينى
كلية الهندسة-جامعة الملك فهد للبترول والمعادن · السعودية
This study investigates the erosion and flow characteristics in a serial arrangement of two similar bevel-edged thin orifice plates with different diameter ratios and orifice spacing. The single or double-orifice arrangements were tested in one-inch-diameter carbon steel pipe. A fully developed pipe flow was ensured well upstream and downstream the orifice arrangement. The numerical analysis was performed on FLUENT 12.1 using the k-ε eddy viscosity model and the discrete phase model (DPM) in conjunction with relevant erosion correlations to predict the flow and erosion features in the orifice spacing and downstream the orifice arrangements. The continuous phase is water while the dispersed phase is sand. To verify the computational results and have a better understanding of the flow regime, an experimental setup was locally designed and manufactured. The flow velocity was measured using Particle Image Velocimeter system (2D-2C PIV) while the pressure drop across the orifice configurations were measured using simple manometers.The effects of various parameters such as pipe flow velocity in the range 1−4m/s, diameters of sand particles within the range 50−400µm, orifice spacing of 1D and 2D, and orifice plate diameter ratios of 0.5, 0.63 and 0.77 have been considered. Validation of the computational code was carried out through several comparisons with previous computational results as well as present experimental PIV measurements. The presence of vena contracta downstream of the first orifice was verified computationally and experimentally, however the presence of vena contracta downstream of the second orifice was found to depend on the orifice spacing. Not only the flow structure between the two orifices and downstream the second orifice was found to depend on the orifice spacing but also the total pressure drop and hydraulic losses.The double orifice configuration with one pipe diameter spacing was found to produce the least pressure drop due to reduced hydraulic losses. The investigation of solid particle erosion in the entire domain revealed the presence of two critical erosion locations downstream the second orifice namely the recirculation and reattachment zones. The least erosion rate was found for double-orifice configuration with 1-D spacing. Although a high-velocity region exists in the spacing between the two orifices, it experienced negligible erosion for large particle size . The results also showed strong dependence of erosion rates on the parameters investigated. Erosion rates increases as orifice diameter ratio and diameters of solid particles decreases and as flow inlet velocity increases.Keywords: erosion, pressure drop, multiple orifices, PIV, two-phase flow