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Since the mechanisms leading to cyclic combustion variabilities in direct injection gasoline engines are still poorly understood, advanced computational studies are necessary to be able to predict, analyze and optimize the complete engine process from aerodynamics to mixing, ignition, combustion and heat transfer. In this work the Scale-Adaptive Simulation (SAS) turbulence model is used in combination with a parameterized lagrangian spray model for the purpose of predicting transient in-cylinder cold flow, injection and mixture formation in a gasoline engine. An existing CFD model based on FLUENT v15.0 [1] has been extended with a spray description using the FLUENT Discrete Phase Model (DPM). This article will first discuss the validation of the in-cylinder cold flow model using experimental data measured within an optically accessible engine by High Speed Particle Image Velocimetry (HS-PIV).

From the point of view of the customer purchasing a car the ecological as well as the price aspect is in the main focus today and in the years that come. This will increase due to global warming, the accelerated depletion of raw materials and significant price increases. Downsizing of spark ignition engines is an opportunity to lessen these shortcomings by decreasing the displacement volume of the engine and for a constant power increasing the load. In the case of extreme downsizing, especially in the case of low engine speed, auto ignition occurs in the air/fuel mixture. As a consequence cylinder pressure tends to exhibit high amplitudes and frequencies, which can lead to engine damage. This paper presents a model which allows linking 3D-CFD with a detailed chemical reaction system. Therefore a three-dimensional numerical model in OpenFOAM is formulated that includes all physical characteristics of a direct-injected, highly charged spark ignition engine.