Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
Full Three-Dimensional versus Three-Dimensional Symmetric Laminar Swirling Flow
Submission Author:
Moises Miranda , RJ
Co-Authors:
Moises Miranda, Andre Damiani Rocha
Presenter: Moises Miranda
doi://10.26678/ABCM.COBEM2021.COB2021-2228
Abstract
Swirling flows are present in nature and in many engineering applications such as turbomachinery, combustion chambers, heat exchangers, and cyclone-type phase separators. The oil and gas industry demand for weight reduction and space occupied on offshore platforms has led to the development of compact separators, an axial inlet hydrocyclone, also known as an in-line separator. In this paper, the capability of the three-dimensional numerical model with periodic boundaries to predict physically realistic results is evaluated and compared with the fully three-dimensional model. The separator consists of a swirling device placed internally in a pipe. The pipe has 50 mm i.d. size and 2500 mm long pipe, and the swirling device is static, where twelve stationary vanes deflect the flow at an angle of 63.5º. Pressure drop, velocity field, vorticity distribution, swirl intensity, and decay were computed for numerical models, and the results were compared. The study considered the flow as laminar, single-phase, isothermal and steady-state. Single-phase flow was chosen to highlight the applications where there is one dispersed phase in the continuous phase, i.e., oil droplets in disposal water, after oil separation. Full hexahedral meshes were generated for the two models using ICEM-CFD, and the simulations were performed using Ansys® Fluent. The mesh of the three-dimensional model with periodic boundaries has approximately 1.13 million control volumes, while the fully three-dimensional model has about 13.5 million control volumes. Both models have been validated with results from the literature. Although the three-dimensional model with periodicity reduces the simulation time by approximately 93%, the model can predict physically realistic results only for Re ≤ 100. The simplified model overestimated the swirl number by 34% for Re = 250 while underestimating the axial velocity by approximately 12% for Re = 300. It was observed a possible transition to an unsteady-state flow between the Reynolds numbers 250 and 300. This value is slightly lower than what is found in the literature and depends directly on the geometry of the swirl generator.
Keywords
Swirling Flow, In-line Separator, Computational fluid dynamics (CFD)
