Design of a Tandem Compressor for the Electrically-Driven Turbocharger of a Hybrid City Car

Within a broader national project aimed at the hybridization of standard city car (the 998 cc Mitsubishi-derived gasoline engine Smart W451), our team tackled problem improving supercharger performance and response. The originally conceived design innovation was that eliminating mechanical connection between compressor turbine. In course study, it turned out is also possible to modify both components extract extra power from use recharge battery pack. This required redesign First, initial configuration analyzed on basis data provided by manufacturer. Then, preliminary assessment turbocharged allowed us identify three “typical” operating points could be used properly turbomachinery. It decided maintain radial for turbine compressor, but latter adding an inducer. For turbine, only minor modifications nozzle guide vanes (NGV) rotor blades shape were deemed necessary, while more substantial modification in order compressor. Fully 3-D computational fluid dynamics simulations rotating machines performed assess their points: kick-in point original turbo (2000 rpm), maximum regime (5500 intermediate (3500 rpm) close minimum specific fuel consumption engine. results presented this paper demonstrate efficiency noticeably improved steady operation all points, its choking characteristics have been improved, surge line has not appreciably affected. net energy recovery calculated demonstrated interesting returns terms storable