Comparative Studies of Different VGT Designs on Performance and Smoke of CRDe Engine

Diesel engines have occupied a significant position in passenger car applications in the present automotive sector. Turbochargers find a very prominent role in diesel engines of all applications in order to achieve desired power and better fuel economy. Gaining higher torque at lower engine speeds with low smoke levels is a very tough task with fixed geometry turbochargers due to availability of lower air mass resulting in higher smoke emissions. Variable geometry turbochargers are capable of providing better torque at lower speeds and reduced smoke emissions on Common Rail Diesel engines. The Variable Geometry Turbocharger types used in this study are straight profile nozzle vanes (sample A) and curved profile nozzle vanes (sample B). The curved profile vanes as seen in sample B results in reduced variation of circumferential pressure distortions. Curved blade profile vane sample results in better low speed torque along with reduced fuel consumption and smoke emissions when compared to straight vane profile sample. Finally 5.5% of improved torque at lower speed was obtained with the equivalence ratio maintaining constant and optimizing the combustion variables ensuring safer smoke limits.