tailieunhanh - Phenomenological model for determining velocity field of lpg jet in combustion chamber of direct injection S.I. engine

The results show that {3 is constant for steady jet but it is not the case for unsteady one. The model will enable us to calculate the velocity profiles of LPG jet after ending injection. This is necessary for research of stratified combustion in direct injection LPG SI engines. | Vietnam Journal of Mechanics, VAST, Vol. 26 , 2004, No 2 (83 - 92) PHENOMENOLOGICAL MODEL FOR DETERMINING VELOCITY FIELD OF LPG JET IN COMBUSTION CHAMBER OF DIRECT INJECTION . ENGINE Bur VAN GA, PHUNG XUAN THO, NHAN HONG QUANG , NGUYEN Huu H UONG University of Danang ABSTRACT . A phenomenological model has been established to predict the velocity distribution of LPG (Liquefied Petroleum Gas) jet in combustion chamber of spark ignition (SI) engine. A shaped coefficient {3 governing the similarity of velocity profiles of LPG jets has been defined based on the theoretical and experimental analyses of turbulent diffusion jets. The results show that {3 is constant for steady jet but it is not the case for unsteady one. The model will enable us to calculate the velocity profiles of LPG jet after ending injection. This is necessary for research of stratified combustion in direct injection LPG SI engines. 1 Introduction Up to now, the models describing the evolution of a fuel jet inside a combustion chamber were often based on a stable and steady jet. This is good suitability for Diesel engine where the diffusion combustion occurs during injection. The direct injection spark ignition engines (GDI engine) is different from Diesel engine because the injection process ends before ignition occurs. It is different also from traditional gasoline engine because the mixture is not homogeny in regime of stratified combustion [5]. So in case of GDI engine, the evolution of jet after ending injection is particularly important with respect to the operating ability [6]. Detailed analyses of the velocity field of turbulent diffusion jet were performed using specific multi-dimensional codes, for example KIVA, FIRES [2] For purpose of simplicity, one-dimensional models have been established to describe the development of fuel jet in the air or in the combustion chamber of engine [8], [IO] . In the later models, t he variation of scalar on jet axis is calculated by integral