Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Numerical analysis of crossflow over one and two rows of cylinders
Submission Author:
Roberta Fatima Neumeister , DF
Co-Authors:
Roberta Fatima Neumeister, Christoph Reichel, Adriane Prisco Petry, Sergio Viçosa Möller
Presenter: Sergio Viçosa Möller
doi://10.26678/ABCM.COBEM2023.COB2023-0404
Abstract
The flow inside a bank of tubes is complex and presents several interaction mechanisms acting at the same time in different positions of the equipment. Simplifying the structures to two cylinders or a few rows can be a way to understand part of the mechanisms and then extrapolate them to a bank of tubes. The flow over a single row in closed space presents wide and narrow wakes, similar to the structure observed in two cylinders side by side, these structures interacting with a second row show a significant change in the incoming flow parameters. The present study aims to show a numerical analysis of the main characteristics of the crossflow in one and two rows of fixed cylinders and to relate the changes in the pressure fields and forces in the cylinders to the expected vibration response. Simulations of rows of cylinders were performed in a domain with a cross-section of 0.193 x 0.05 m and a length of 0.8 m. Five and ten cylinders with an external diameter of 25 mm were applied. The longitudinal and transverse spatial ratio is 1.26 and all cylinders were fixed. The continuity and Navier-Stokes equations were solved using the Large Eddy Simulation with the Smagorinski-Lilly subgrid model with dynamic stress in Ansys Fluent 19. The Reynolds number is 5 x 104, based on the gap flow velocity and the diameter of a single cylinder. The transient analysis is performed with a time step of 1 x10-5 s and the 10-6 convergence criterion is used for all monitored variables. Preliminary results show wake asymmetry after the first and second rows of cylinders. There is an asymmetry between the velocity in the gaps between the cylinders indicating a redistribution of the flow, increasing and decreasing the velocity in the gaps between the cylinders. This velocity and pressure distribution influences the forces along the cylinders showing an increase in forces coefficients at some cylinder positions. The non-homogeneous distribution of velocity in the gaps is an important factor in determining the vibrational response, as the models use this information as an input parameter to determine the instability limits.
Keywords
Numerical analysis, cross-flow, Row of cylinders, flow-induced vibration
