Influences of nozzle vane clearance and opening on vibration characteristics of rotor blades

To study the vibration problem of vehicle turbocharger turbine, a variable geometry radial turbine was adopted to investigate the resonant responses of rotor blades in different nozzle vane clearances and openings. The results show that the vibration of rotor blades intensifies and its dynamic stress increases with the decrease of nozzle vane opening. While the increase of nozzle vane clearance will intensify the vibration of turbine rotor, thus increases the dynamic stress of rotor blades. The stress stiffing caused by the rotation of the turbine has significant iMPact on the natural frequency of the rotor. With the increase of rotation speed of the turbine, the natural frequency of the rotor increases. The resonance points of the turbine next to the 1st and 2nd order of natural frequency are probably induced by the fluctuating aerodynamic excitation. And the 1st order resonance of the rotor locates at the trailing edge of the rotor blade while the 2nd one is at the leading edge of rotor blade. In the process of vibration, each blade shows different response characteristics, and the responses values are according to sinusoidal curves.