Journal of Vibration and Sound

Journal of Vibration and Sound

Investigating the effect of bearings distance on the critical speeds of a turbocharger

Document Type : research article

Authors
Sepehr Goodarzi 1
Abbas Rahi 2
1 دانشکده مهندسی مکانیک و انرژی، دانشگاه شهید بهشتی
2 Faculty of Mechanical and Energy Engineering, Shahid Beheshti University, Tehran, Iran
Abstract
Turbocharging is an auxiliary system that increases the output power and efficiency of internal combustion engines by injecting more air into the combustion chamber. Studying their dynamic behavior and knowing their critical speeds is important due to their widespread use in automobile engines, locomotives, and aerospace industries. In this research, first, an analytical model of 16 degrees of freedom is presented to calculate the natural frequencies of the turbocharger, and based on it, the governing equations are derived. Then, the results obtained from the analytical solution of the governing equations are validated using the finite element method. Next, the first to fourth critical speeds of the system are calculated at different distances of the bearings on the shaft and the Campbell diagram of the system is analyzed. Finally, the frequency response of the system due to the mass imbalance in different positions of the bearings is checked. The results show that by increasing the distance between the bearings, the first and second critical velocities of the system increase, and the amplitude of the system vibrations at the first resonance frequency decreases.
Keywords
Turbocharger
critical speeds
Campbell diagram
unbalance
bearings
Subjects
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