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

Mehdi Sadeghi (1, 2) , Karine Truffin (1, 2) , Brian Peterson (3) , Benjamin Böhm (4) , Stéphane Jay (1, 2)

1 IFPEN - IFP Energies nouvelles
2 Institut Carnot IFPEN Transports Energie
3 School of Engineering [Edinburgh]
4 TU Darmstadt - Technische Universität Darmstadt - Technical University of Darmstadt

The bivariate two dimensional empirical mode decomposition (Bivariate 2D-EMD) is extended to estimate the turbulent fluctuations and to identify cycle-to-cycle variations (CCV) of in-cylinder flow. The Bivariate 2D-EMD is an adaptive approach that is not restricted by statistical convergence criterion, hence it can be used for analyzing the nonlinear and non-stationary phenomena. The methodology is applied to a high-speed PIV dataset that measures the velocity field within the tumble symmetry plane of an optically accessible engine. The instantaneous velocity field is decomposed into a finite number of 2D spatial modes. Based on energy considerations, the in-cylinder flow large-scale organized motion is separated from turbulent fluctuations. This study is focused on the second half of the compression stroke. For most of the cycles, the maximum of turbulent fluctuations is located between 50 and 30 crank angle degrees before top dead center (TDC). In regards to the phase-averaged velocity field, the contribution of CCV to the fluctuating kinetic energy is approximately 55% near TDC.

Keywords: In-cylinder flow; Bivariate 2D-EMD; Turbulence; Large-scale organized structure

Domains: Environmental Sciences

Mehdi Sadeghi, Karine Truffin, Brian Peterson, Benjamin Böhm, Stéphane Jay. Development and Application of Bivariate 2D-EMD for the Analysis of Instantaneous Flow Structures and Cycle-to-Cycle Variations of In-cylinder Flow. Flow, Turbulence and Combustion, 2021, 106 (1), pp.231-259. ⟨10.1007/s10494-020-00197-z⟩. ⟨hal-03136997⟩