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DEVELOPMENT OF OFF-DESIGN TURBOCHARGER MODELLING COMBINED WITH 1-D ENGINE MODEL

The present work aims to carry out an off-design turbocharger modelling powered by exhaust gases from a Wärtsilä 20V34SG engine. First of all, 1D engine model was already developed in GT-Power software while considering a thermodynamic turbocharger modelling with constant isentropic efficiencies. Secondly, by using the results from 1-D engine model, the off-design turbocharger modelling is calibrated separately in EES software, taking into account compressible assumption, triangle velocities and geometric dimensions. The case study is derived from a R&D project (ANEEL PD-06483-0318/2018) that targets to cool and dehumidify the intake air at compressor’s upstream through a cooling coil, thereby allowing engine’s operation at reduced knocking conditions. The brake mean effective pressure (BMEP) is varied in the range of 20 to 23.45 bar, corresponding to brake power from 8.7 to 10.2 MW, respectively. With the off-design turbocharger modelling it is possible to analyze its operational behavior under higher BMEP, hence, allowing to predict some important parameters. The results showed that the turbocharger is operating within the manufacturer’s limit for BMEP of 23.45 bar, presenting total-to-static isentropic efficiencies of 0.81 and 0.784 for compressor and turbine, respectively, rotational speed around 28135 RPM, pressure ratio at compressor of 4.567 and maintaining control on waste-gate valve.