Abstract
Pressure drop due to single phase flow of water and two phase flow of air-water mixture through thin orifices in horizontal pipes have been numerically investigated. Two-phase computational fluid dynamics (CFD) calculations, using Eulerian–Eulerian model have been employed to calculate the pressure drop through orifices. The operating condition covers the gas and liquid superficial velocity ranges Vsg=0.3–4 m/s and Vsl=0.6–2 m/s, respectively. The local pressure drops have been obtained by means of extrapolation from the computed upstream and downstream linearized pressure profiles to the orifice section. Simulations for the single-phase flow of water have been carried out for local liquid Reynolds number (Re based on orifice diameter) ranging from 3×104 to 2×105 to obtain the discharge coefficient and the two-phase local multiplier, which when multiplied with the pressure drop of water (for same mass flow of water and two phase mixture) will reproduce the pressure drop for two phase flow through the orifice. The effect of orifice geometry on two-phase pressure losses has been considered by selecting eight different orifice plates with two area ratios (σ=0.73 and σ=0.54) and four different thicknesses (s/d = 0.025-0.59). The results obtained from numerical simulations are validated against experimental data from the literature and are found to be in good agreement. Keywords: Orifice, Pressure drop, Two phase flow, Computational fluid dynamics, Area ratio, Discharge coefficient
Highlights
Elements in flow rate measurement and regulation
Knowledge of pressure drop for two-phase flow d by selecting two pipes of 60 mm and 40 mm inner diameter and six different through valves, orifices and other orifice plates with two pipe fittings are important for the control and operations of industrial area ratios (σ = 0.73 and σ = 0.54) and three different thicknesses
If the orifice is thick (Fig.1b), downstream of the vena contracta, the flow reattaches to the wall within the length of the geometrical contraction and can even develop a boundary layer flow until it Research article Indian Society for Education and Environment
Summary
The orifice is one of the most commonly used (Chisholm, 1983; Simpson et al, 1983; Morris, 1985). Some of them cover only a limited range of Because of its simple structure and reliable performance, operating conditions, and the errors of some are far the orifice is increasingly adopted in gas-liquid, two-phase beyond the limit of tolerance. They are not widely used flow measurements. Few flow uniformity and mass distribution downstream of experimental studies, reported in the literature often refer manifolds and distributors. They are used to to a limited set of operating conditions. Some investigations have been made on the theory and experiment of resistance characteristics of orifices and some (b)
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