Surface erosion by high-speed combustion waves

Abstract

Violent high-speed combustion events lead to erosive destruction of piston surfaces under knocking conditions in internal combustion engines. The details of the damaging mechanism are the subject of an extensive controversy. In this paper, we present and support a new theoretical model for one possible mechanism causing erosive destruction due to high-speed combustion waves. The theory involves the initiation and resonant amplification of Rayleigh surface waves in the elastic piston material. Intense peak stresses develop very close to the material surface and may explain the erosive nature of the observed damage. We support the proposed theory by research engine experiments as well as by direct numerical simulations for a simplified two-dimensional model problem. The model computations include the gasphase high-speed combustion and the elastic wave propagation in the solid. In this paper, we focus on mechanical stresses, while we leave a detailed investigation of and comparison with thermal loads for future work.