Análise das condições iniciais para simulação do escoamento em golfadas utilizando o modelo lagrangeano de seguimento de pistões

Abstract

Two-phase slug flow is present in various industrial processes, especially in the oil industry, with the production and transportation of oil and gas. Slug flow is characterized by the intermittent succession of liquid slugs, which have a large momentum, that may contain bubbles of compressible gas, followed by elongated bubbles of gas occupying much of the cross-section of the pipeline. Few mathematical models for this complex flow can be found in the literature. Among those, the most common models are the Eulerian two-fluid and drift flux and the Lagrangian slug tracking. Slug tracking modelling requires that some parameters, such as gas and liquid superficial velocities, liquid slug and bubble lengths, and gas and liquid fractions are provided for simulations. In this work, four methodologies for the initialization of flow in a simulator with the slug tracking modelling are evaluated. The first methodology consists in using values obtained from experimental data. The second is a list of values distributed around the standard deviations and mean values of the experimental data. The third is the use of previously simulated data and calculating the gas superficial velocity with the Bendiksen (1984) formulation. The last one was the use of the simulated bubble and liquid slug lengths, calculation of the gas fraction and the use of the other parameters determined with the second methodology. Experimental measures were taken to obtain data for validation and comparison of the results obtained using the four methodologies. When evaluating the results, it was noticed that methodology 1 is the one that most approached the experimental data at the beginning of the flow. Methodology 2, however, presented good results for the velocity of the elongated bubble. While methodology 3 provided good results for the elongated bubble lengths and liquid piston and inflow frequency of the bubbles in the pipeline. The methodology 4 was the one that distanced itself more from the experimental results, mainly for the lengths of the elongated bubble. As the objective of the present work was the determination of the best methodology to obtain the initial independent conditions of the use of experimental data, after analyzing the results it can be affirmed that methodology 3 presented the best results for the characteristic parameters of slug flow.