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

Abstract

The present work aims to carry out an off-design turbocharger modelling
powered by exhaust gases from a Wärtsilä 20V34SG engine. First of all, 1-
D 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.