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

The present work aims to carry out an off-design turbocharger modellingpowered by exhaust gases from a Wärtsilä 20V34SG engine. First of all, 1-D engine model was already developed in GT-Power software whileconsidering a thermodynamic turbocharger modelling with constantisentropic efficiencies. Secondly, by using the results from 1-D enginemodel, the off-design turbocharger modelling is calibrated separately inEES software, taking into account compressible assumption, trianglevelocities and geometric dimensions. The case study is derived from a R&Dproject (ANEEL PD-06483-0318/2018) that targets to cool and dehumidifythe intake air at compressor’s upstream through a cooling coil, therebyallowing engine’s operation at reduced knocking conditions. The brakemean 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 theoff-design turbocharger modelling it is possible to analyze its operationalbehavior under higher BMEP, hence, allowing to predict some importantparameters. The results showed that the turbocharger is operating within themanufacturer’s limit for BMEP of 23.45 bar, presenting total-to-staticisentropic efficiencies of 0.81 and 0.784 for compressor and turbine,respectively, rotational speed around 28135 RPM, pressure ratio atcompressor of 4.567 and maintaining control on waste-gate valve.