This study presents a numerical investigation using the finite element method on the vibratory behavior of a single spool gas turbine designed for unmanned aerial vehicle applications. The shaft of the rotor-bearing system is supported on a front bearing composed of a deep groove ball bearing with a vibration absorber element and a rear squeeze film damper bearing. Three radial clearances for the squeeze film damper were analyzed to determine the best geometric configuration for the rear bearing, considering the rotordynamic performance of the entire system. Whirl speeds and unbalanced system responses were carefully evaluated to determine the best radial clearance for the squeeze film damper. After defining the best radial clearance, a transient analysis was performed to simulate the transition of the system through resonance, and a spectral map is presented to illustrate the vibratory behavior of the system considering the influence of all related important frequencies. The rotordynamic behavior of the system is predicted, and vibration problems are avoided. Its mechanical drawings were released to manufacturing, and the first prototype is in the experimental test phase, thus indicating that the numerical results presented in this study are consistent.

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Gas turbines are very important because they can be used in several areas, such as aeronautics and electric power generation systems. The operation of a gas turbine can be done by less pollutant fuels when compared to traditional kerosene, for example, resulting in less degradation to environment. Gas turbines may fail from a variety of sources, with the possibility of serious damage results. In this work, the structural integrity of the hot disc of an aeronautical gas turbine is addressed. Several numerical analyses have been performed by the finite element method: Temperature Distributions, Thermal Stresses and Dilatations, Structural Stresses and Deformations, Modal Behaviors and Fatigue Analysis. Creep of blades has also been considered. These are the most important failure modes that can happen to the studied hot disc under operating service. All these analysis have been performed considering the boundary conditions at the design point with maximum rotational speed. The mesh of the problem has been strictly evaluated by adaptive refinement of nodes and elements combined with a convergence analysis of results. Then, the material and basic properties of the hot disc have been defined to assure a normal operation free from failures. Therefore, the mechanical drawings of the studied hot turbine disc have been released for manufacturing and the construction of the first prototype of the aeronautical gas turbine is in testing phase showing that the results presented in this work are consistent.

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A mathematical model of a coupled cylindrical shell-fluid dynamic interaction problem based on an axisymmetric finite element analysis is presented. The dynamic solution of the problem is separated into axisymmetric and nonaxisymmetric behaviors and a method is presented for the nonaxisymmetric transient response analysis. It is employed to estimate the natural frequencies of the cylinders partially filled with water. The theoretical predictions are compared with the experimental results and it is shown that there eixsts a good correlation between the two sets of results.

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