Phenomenology and analysis of gas pressures at low-speed pre-ignitions

Authors

Dr.-Ing. Christoph Beerens, Dipl.-Ing. Rainer Fischer, Dipl.-Ing. Christian Trabold, MAHLE GmbH

Year

2019

Summary

The phenomenon of low-speed pre-ignition (LSPI) has gained widespread significance with the growing implementation of downsizing concepts in gasoline engines. Failures of piston top land, second land or skirt are inducing catastrophic engine failures both in testing and field applications. In order to assess the influence of LSPI on the compo-nents’ stability the application of realistic load cases is crucial. Classical approaches are not applicable here any more.
In this publication a new method is presented, which employs measurement and simulation in order to derive realistic load cases for LSPI influence on pistons. This is done by correlation of gas dynamics measurements and simulations in order to model the propagation of pressure waves during LSPI events.
Problems still exist due to the stochastic nature of LSPI pressure amplitudes and subsequent damage accumulations leading to a piston failure. In spite of that, conclusive evidence found about the damage mechanisms allows for a much improved understand-ing of actual engine failures.

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