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, Karine Truffin, Brian Peterson, Benjamin Böhm, Stéphane Jay

Research output: Contribution to journalArticlepeer-review

Abstract

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.
Original languageEnglish
JournalFlow, Turbulence and Combustion
Early online date10 Aug 2020
DOIs
Publication statusE-pub ahead of print - 10 Aug 2020

Keywords

  • In-cylinder flow
  • Bivariate 2D-EMD
  • Turbulence

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