Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Comparative Analysis of the Rotordynamic Coefficients of a Plain Seal
Submission Author:
Kaíque César Macedo Chagas , MG
Co-Authors:
Kaíque César Macedo Chagas, Leonardo Cabral, Aldemir Ap Cavalini Jr, Valder Steffen Jr, Franco Barbi
Presenter: Kaíque César Macedo Chagas
doi://10.26678/ABCM.COBEM2023.COB2023-0837
Abstract
Mechanical seals are components installed in rotating machines in order of reducing the leakage flow of the lubricating fluid by restricting the space between the stator and rotor and, consequently, increasing the frictional forces between the fluid and the walls. Therefore, most studies related to this topic are dedicated to minimizing the leakage flow of the lubricating fluid, that is, few works in the literature have analyzed the behavior of the dynamic coefficients of the seals. One of the works dedicated on Analysis of Rotordynamic Coefficients of plain seals was developed by the Rotating Machinery and Controls (ROMAC) Industrial Research Program, with a model based on empirical relations between the shear stress acting on a wall and the relative velocity of a fluid concerning this wall, using equations in axial and circumferential directions for the stator and rotor. Then, after a perturbation analysis, in which a displacement and an angular velocity are imposed to the rotor center, a set of zeroth order equations and a set of 1st order equations are obtained and solved along the length of the seal and for various perturbation angular velocities to determine the pressure distributions, due to the 1st order perturbation, for each perturbation angular velocity and along the length of the seal. In this way, the pressure is integrated along the area of the seal in contact with the lubricating fluid and the rotor response forces to imposed displacements, velocities, and/or accelerations are obtained. Since dynamic coefficients are related to response forces, dynamic coefficients are determined using a curve fit. The objective of this work is to develop a computational algorithm to determine the rotordynamic coefficients of a plain seal and compare the obtained results with those determined by the model. The results obtained by using the developed algorithm are very close to the reference (ROMAC), with some exceptions, since the linear system solved in the curve fitting is very sensitive, and, small changes in the vector of the independent terms may cause significant variations in the results obtained for the dynamic coefficients of the seal.
Keywords
rotordynamic coefficients, Perturbation Analysis, Curve Fit
