EXPERIMENTAL AND COMPUTATIONAL INVESTIGATIONS OF A SQUEEZE FILM DAMPER SUPPORTED ON ROTORS

Abstract

Squeeze film dampers (SFDs) are used to reduce the vibration amplitude of high-speed rotors. In this context, an SFD has been developed to meet the requirements of high-speed rotating shafts that are generally used in high-speed rotor application. In this study, the effect of SFD process parameters (rotation of shaft, oil pressure inside the damper, and oil blend sample) on the vibration amplitude of the shaft on the x-axis and vibration amplitude of shaft in the z-axis, is investigated, during the rotation of the flexible shaft up-to-speed 10000rpm. The oil sample used in the present work was mixed with 10%,20%,30%,40%, and 50% kerosene oil (Dynamic viscosity 1. 1287mPa.S), in independent experiment, with 5W30 crankcase oil (Dynamic viscosity 75.483 mPa.S) and used variable high-pressure oil supply system up to120bar. The Taguchi approach (L25-orthogonal array) is utilized for experiment design, and the experimental findings are examined using analysis of variance (ANOVA). The table of response for an average value of the vibration amplitude of the shaft in the x-axis and z-axis, indicates that supply oil pressure is the most significant factor for shaft amplitude along the x- and z-axes, while blending Newtonian fluid is important for reducing the vibration amplitude. Analysis through ANOVA also supports similar results. It has also been discovered from SNR graph, that Pressure-100bar, Speed-4000rpm, Blend-40% (P5S2B4) in the x-axis and Pressure-100bar, Speed-4000rpm, Blend-50% (P5S2B5) in the z-axis are the optimal levels of process parameters for reducing vibration amplitude. The successful experimental validation confirms the accuracy and reliability of the optimized values for vibration control. The experimental design used in this study uses the Box-Behnken design (BBD) method, which is a widely used approach in experimental design. The study also incorporates Response Surface Methodology (RSM) and Analysis of Variance (ANOVA) to optimize the input parameters and assess the statistical significance of the model. vi Desirability-based optimization is used as a means to attain the intended objectives of vibration control. The artificial neural network (ANN) model has shown somewhat reduced prediction errors and a greater coefficient of determination compared to the response surface methodology (RSM) for both the x and z axes of vibration amplitude. During the fourth stage of our experiment, the position of the load was changed in intervals of 10 to 50 cm, in steps of 10 cm, from the end support. A distinct pattern in the amplitude of shaft vibrations in the x and z axes was observed. The amplitude noticeably increased as the load was closer to the support, and decreased correspondingly when the weight was moved farther away, especially beyond the midway of the shaft length. In the second phase, we replaced the end support with a squeeze film damper (SFD) and directed our attention to assessing vibration amplitudes along the X and Z axes. This analysis included employing different oil samples with varying viscosities. Significantly, when a steady load was imposed, replicating the original configuration without the SFD, interesting results were noted. The findings demonstrated a constant reduction in vibration amplitude for both axis as the viscosity of the oil samples rose, ultimately reaching an ideal level. This finding highlights the substantial influence of oil thickness on determining the overall vibration properties in a system that employs a squeeze film damper. These findings provide valuable insights for developing and implementing Squeeze film dampers (SFD) in rotating shaft applications at high speeds, contributing to improved vibration control and enhanced performance.