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Abstrakt
The dynamic behaviour of a bladed disk-turborotor-bearing system is studied employing analytical, numerical and experimental methods. The system consists of several subsystems such as turbine disk, blades, bearings, support pedestals etc. In order to completely understand the dynamic behaviour of the turborotor system an appropriate model for each individual component of the system is first developed. The individual components are modelled to include various design parameters and the effect of these parameters on the vibrational behaviour is studied. The vibration studies on the individual components are carried out using Rayleigh-Ritz method boundary characteristic orthogonal polynomials as assumed shape functions. The individual components are then assembled using the finite element technique. The turborotor system is studied from a system point of view and the natural frequencies and mode shapes are obtained for various rotational speeds. The results show that the natural frequencies of the system are different from those obtained by analyzing individual components, suggesting that a system approach must be adopted for proper design of a turborotor system. The amplitude of vibration and stresses due to harmonic and centrifugal loading on the blades and the disk are also obtained. The results indicate that for the turborotor speed of operation, the centrifugal loading is the major factor in determining the critical stresses in comparison to the gas forces on the blade modelled as harmonic loading. Experimental validation of the analytical model is carried out and suggestions for future work are given.
