Numerical Analysis And Experimental Research On Turbocharger Rotor Faults

Along with the rapid developing of Chinese economy, the demand for internal combustion power plant grows higher and higher. The small internal combustion locomotive with high-power and the matched exhaust gas supercharger needs to be with high-pressure ratio, high efficiency, safety and reliability. The technology of the exhaust gas turbocharger promotes the interior turbine rotation by using inertial impact force of the gas of the engine. And it drives the same axis of impeller to rotate, the high-speed revolution impeller raise the kinetic energy of filtered air and pressure substantially. It slows down the speed of diffuser to further diffuse, and then it goes into the air cylinder. As the rotor of interior core moving parts it has the decisive functions. Due to the bad working environment of turbine rotor, working at high-speed and high pressure, centrifugal force, pneumatic pressure, resonance etc, it’s easy to cause cracks at the joint of frictional welding area. The reason of causing the rotor’s axis cracks has different kinds, for instance, the problems of product designing, manufacturing technique, and resonance etc. Therefore, to find the reason of causing the rotor axis’cracks, it’s very important to avoid the similar failure and propose some valuable references in the future.This thesis mainly includes three jobs here.First, this chapter compressively applies the basic theory of failure analysis, measurement technique, mechanical statics and basic theory of dynamics. It adopts the XL-30W/TMP scanning electron microscope to examine the wheel disc, appearance of fracture of the principal axis and metallographic structure, it also adopts the emission spectrometer to measure the matrix chemical component, it uses Rockwell apparatus to measure the matrix and the surface hardness of hardening layer of the shaft neck, it exploit MH-6micro-hardness tester to measure the shaft neck surface and hardness gradient of the welding areas. The result shows that the axis cracking area happens at the friction of welding area, failure is caused at the cracking area which exists the residual stress and weak bonding strength. And it proposes analysis methods of supercharger rotor spindle’s cracking phenomenon while it’s working.Second, using the software of finite element analysis will have statics analysis and modal analysis for the rotor spindle. It turned out that the structural designing doesn’t exist any evident defects, its design strength conforms to the application demand; it confirms the working condition’s vibration frequency is lower than the inherent frequency. While working at this frequency, the welding surface of friction can’t generate any breakage. Finally, according to the above analysis results, it proposes improvement direction for the supercharger rotor spindle friction welding technology, and it also prevents this kind of repeating failure, it reduces some unnecessary economic losses, it avoids some possible existing casualties, and it increases the production’s total body mass and integrality of the structure.This paper combines the finite element analysis and traditional medal metallographic analysis, to realize the performance simulation of the mechanic axis. Analyzing the rotor spindle’s fatigue makes more scientific and theoretical foundation, and provide theoretical basis for the designers who design and analyze.