Development and Application of Bivariate 2D-EMD for the Analysis of Instantaneous Flow Structures and Cycle-to-Cycle Variations of In-cylinder Flow

Abstract

EMD for the analysis of instantaneous flow structures and cycle-to-cycle variations of in-cylinder flow', Flow, Turbulence and Combustion.

ECFM-LES modeling with AMR for the CCV prediction and analysis in lean-burn engines

“…It was applied to a velocity field constructed with a large-scale organised synthetic vortex and relatively small-scale isotropic homogeneous turbulence. Subsequently, the methodology was also applied to high-speed PIV measurements in the symmetry plane of the tumble of an optically accessible engine [10]. Both results confirmed that the turbulent part could be separated from the large-scale organized motion based only on the instantaneous velocity field, following:…”

“…R2P1. As confirmed in [10], EMD is suitable for the analysis multi-cycle flow fields in engines as it is not limited by a statistical convergence criterion. Other decomposition methodologies exist in the literature.…”

“…with U LF the large-scale motion of low-frequency and U HF the turbulent fluctuations of high-frequency. In [10], the EMD method has been adapted to the analysis of PIV fields in complex, time-dependent geometries such as those encountered in engine configurations where the size of the velocity field changes with the piston position. R2P1.…”

“…The EMD method used in this study is modified and improved in terms of the mode combination strategy. In [10], an imposed number of modes N IMF is predefined for the decomposition in both horizontal and vertical directions and thus the velocity field needs to be interpolated into a uniformly sampled square grid. Once the decomposition is completed, pseudo IMFs are combined into N IMF IMFs, and finally only the last IMF and the residual are retained in the Low-Frequency (LF) part which represents the largescale motion.…”

“…-Thirdly, additional innovative post-processing tools are applied to get insights into the correlation between CCV and the turbulent flow field variability, namely Empirical Mode Decomposition (EMD) technique [10] and a tumble shape characterisation analysis tool (C 3p ) [11].…”