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The ideal torque curve of automotive engines should be high and flat from low engine speed. To achieve this, we installed a variable nozzle turbine (VNT) turbocharger to a retail natural aspirated (NA) small gasoline engine. In the VNT turbocharger, variable vanes are set around the turbine wheel and form nozzles that changed the flow velocity of the exhaust gas. The vane position was controlled to adjust intake pressure at a target. As a result, the maximum torque improved by 27% and the engine speed at maximum torque was lowered by 1550rpm. A flat torque curve was achieved from 5450rpm to 8000rpm.

Cylinder pressure is used for the closed-loop ignition angle control of a gasoline engine. This paper focused on the crank angle position where the maximum cylinder pressure reached (θPmax) and the relationship between the θPmax and the ignition angle. This closed-loop control set the θPmax a target value with an initial ignition angle and does not need a detailed ignition angle map. Response time and deflection with the target value are examined with a test bench. The θPmax target, ATDC 18 deg. is confirmed in consideration of the effect of knocking and the exhaust gas composition. The target ignition angle was varied step by step within a limit of upper and lower values, the response was observed and each gain was decided. At the engine speed of 5000 rpm, the duration to reach a steady value of θPmax is 0.10 s and the response time of ignition angle is 0.02 s.

In this study, the background gas of the droplet vaporization was concerned and simulated numerically using ANSYS fluent code. The new type, engine-like, condition of high pressure chamber and high temperature environment was considered to conduct experiment on kerosene droplet evaporation. 2D geometry of domain simulation was discretized in the very fine quadrilateral meshes. The numerical approach was solved using implicit scheme of compressible gas solver (density based). Temperature dependent properties of air are expressed for gas material properties. As the study concerning on high pressure condition the equation state of Peng-Robinson was expressed in simulation. Governing equations of mass, momentum and energy were solved by the second order upwind for flow, turbulent kinetic energy and turbulent dissipation rate. Standard k-ε model was used to solve turbulence flow in the spatial discretization.