Abstract
Keywords:
Efficiency, Diesel engine, downsizing, operating range, matching, two-stage turbocharging, pulse, twin-scroll turbine, 1D simulation, engine test
Abstract:
A general trend of automotive development is the reduction of engine size without performance degradation. Main purpose of that is above all to make the engine work on higher load points where efficiency is greater, and also to reduce vehicle mass. The main benefit of this “downsizing” tendency is CO2 emissions reduction, whilst preserving, and even by improving driver perception (smoothness, power…).
To satisfy this request, especially for Diesel engines, multi-stage turbocharging brings specific power and power- to-weight increase, without any engine operating range reduction. However, compared to a standard displacement engine with single-stage turbocharging, this kind of solution applied to a reduced displacement engine can diminish response low engine speeds, particularly during pull-away. So, as increased turbocharging boost compensates for smaller engine capacity, the poorer response has to be minimised.
To resolve this problem whilst maintaining CO2 as a priority, LMM has been working for several years now on new solutions, whose main purpose is to improve turbocharged engine operating range. To complement LMMs long experience in charge boosting, intensive simulation and experimental work has been performed.
A solution applied to series turbocharging named “Twin-Flow A52”, which offers interesting economic and technical trade-odds, is presented here. The concept, it’s methodology, the simulation work, and finally, initial tests on a small Diesel demonstrator are presented.