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Wavelet Analysis of In-Cylinder LDV Measurements and Correlation Against Heat-Release

På svenska

Author

  • Fredrik Söderberg
  • Bengt Johansson

Summary, in English

Wavelet analysis was used to calculate turbulence and mean velocity levels for LDV measurements made in a four valve spark ignition engine. Five different camshafts were tested, and they produce significantly different flow behaviour. The standard cam gives tumble and with valve deactivation, swirl is produced. One camshaft with early

inlet valve closing and two camshafts with late inlet valve

closing were also tested. The wavelet toolbox for Matlab

version 5.1 has been used for the wavelet calculations.



The wavelet technique produces both time resolved and frequency resolved velocity information. The results indicate some influence of the turbulence frequency content

on the rate of heat release. Correlation against eatrelease can be seen for different scales of turbulence.

The breakdown of the tumble (low frequency turbulence) into high frequency turbulence can be seen clearly. This

transition is not as clear with a swirling flow, where all frequencies are magnified equally at top dead center. The

choice of wavelet does not have a major impact on the

results.

Department/s

Publishing year

1998

Language

English

Publication/Series

SAE technical paper series

Volume

107

Document type

Journal article

Publisher

Society of Automotive Engineers

Topic

  • Vehicle Engineering

Keywords

  • LDV
  • Wavelet
  • Engine
  • Combustion

Status

Published

ISBN/ISSN/Other

  • ISSN: 0148-7191