Simulation and scale-up of a centrifugal compressor for a turbocharger of a lean combustion engine employing 1-D and 3-D design and geometrical modification of the impeller

Nowadays, turbochargers application has been essential to increase the internal combustion engine's power and reduce the emissions while engine size remains unchanged. In this research, the scaling of a centrifugal compressor of a turbocharger is investigated to increase the mass flow rate by 15 percent. In contrast, compressor pressure ratio, efficiency, and performance range should be preserved, and the general dimension will be unchanged to cut the construction costs. This study has focused on the purpose in which the compressor should be compatible with the turbine, so the rotational speed is almost unchanged by the geometrical modification during the investigation. Two scenarios are considered, including reducing the hub radius, increasing the shroud radius, and changing the location of the splitter blade. In the first scenario, the hub radius is decreased by 1.8 mm, and only a 2 percent improvement in mass flow rate is obtained. In the second scenario, in addition to reducing the hub radius, the shroud radius is increased by 1.63 mm. The splitter blade is located at 35 percent of the meridional coordinate. One-dimensional design and three-dimensional simulation show that the mass flow rate is improved by 16.5 percent. The study introduces a reliable analytical-numerical method to scale up a centrifugal compressor without any significant modification on general dimensions, leading to a drastic change in the turbocharger casings and an increase in manufacturing costs). The method is a general way to scale up a centrifugal compressor extended for turbochargers or other applications.