Separation of combustion noise and piston-slap in diesel engine—Part II: Separation of combustion noise and piston-slap using blind source separation methods

Abstract

This paper is devoted to blind separation of combustion noise and piston-slap in diesel engines. The two phenomena are recovered only from signals issued from accelerometers placed on one of the cylinders. A blind source separation (BSS) method is developed, based on a convolutive model of non-stationary mixtures. We introduce a new method based on the joint diagonalisation of the time varying spectral matrices of the observation records and a new technique to handle the problem of permutation ambiguity in the frequency domain. This method is then applied to real data and the estimated sources are validated by several physical arguments. So, the contribution of the piston-slap and the combustion noise can be recovered for all the sensors. The energy of the two phenomena can then be given with regards to the position of the accelerometers.