Further Investigation into the Statistical Properties of Reciprocating Engine Turbulence

Abstract

In order to further develop appropriate general methodologies for analyzing the properties of reciprocating engine turbulence and to enhance a fundamental understanding of the in-cylinder turbulent flow phenomena, basic aspects in the correlation and frequency spectral structure of engine turbulence were considered, particularly the estimation of a characteristic time scale, the macro time scale, or simply the time scale, on the analogy of the integral time scale of turbulence for stationary flows. Applications to the study of turbulence properties in an automotive engine under variable swirl flow conditions are presented, including an insight into the probability density function of the engine turbulence. In addition, evaluation of cross terms, which arise in the momentum equation when unconventional averaging is used for the in-cylinder velocity, was provided with reference to the cycle-resolved data reduction procedure previously developed.