Study of load level of bearing-outlet units of turbocharger with impellers from composite materials

Abstract

The procedure for the calculation of loading reduction of the bearing assembly of the automotive diesel engines turbocharger forced aspiration by using composite materials for the rotor impellers is decribed. The most significant parameters for such an assessment are the reaction force in the bearing oil layer, the frictional moment in the oil layer, and the relative internal and external clearances in the bearings. The software Flexible Rotor was used as the main computational tool of this study. This software is registered in the register of applied programs for computers No. 2006611094. The study considered the following design options for rotors with a combination of wheels made of different materials: 1) impellers made of traditional metal materials compressor wheel made of aluminum alloy, turbine wheel made of heat-resistant nickel alloy (basic version); 2) сompressor wheel made of composite, turbine wheel made of heat-resistant nickel alloy; 3) aluminum alloy compressor wheel and composite turbine wheel; 4) a compressor wheel and a turbine wheel made of composites. According to the evaluation studies, the most rational options for variable wheel combinations in the rotor design are proposed. In general, the results of the calculations showed that a decrease in the mass-inertial characteristics of the rotor due to the use of composite materials with a low density leads to a decrease in bearing loads and a reduction in friction losses by up to 3 times. The established reduction of the friction torques reduces the intensity of the dissipation of mechanical energy in the bearings. This has a positive effect on the energy efficiency of the turbocharger and reduces the temperature of oil heating from friction.