Mesh Movement Method for Transient Simulation of Annular Cavities: Application to Prediction of Fluid Forces in Squeeze Film Dampers

Abstract

Computational fluid dynamics (CFD) simulations are used in addition to experimental work in turbomachinery research. Increasing computational power and feasibility of a reliable CFD-solver makes it possible to solve complex problems. Different approaches for calculation of dynamic fluid forces use the assumption of a circular centered orbit (CCO) to model the problem using stationary simulations. Because CCO assumption does not properly match the real movement of the rotor, transient simulations are necessary for more realistic models. This work describes some mathematical algorithms that map a cylindrical, annular cavity into a rectangular, dimensionless coordinate system. According to grid quality aspects under displaced rotor position and compatibility with geometric boundary conditions one method is chosen to be the most suitable for the desired purpose. The proposed mesh movement approach combined with more realistic boundary conditions concerning an open-ended bearing was used for the prediction of fluid forces in a squeeze film damper (SFD) executing CCOs at six different orbit radii between 0.4 and 0.9 relative to the nominal radial clearance. The parameters of the numerical model—for example, damper configuration, supply pressure, orbit radius and whirling frequency—were used on an SFD test rig to generate experimental results. The experimental and numerical results are compared and discussed.