Search Results

The efficiency of engine operations, i.e. cold start, transient response and operating at idle, depends on the capability of the injection fuel system to promote a homogeneous mixture formation through an efficient interaction with engine fluid dynamics and geometry. The paper presents the development and the application of a methodology for running a CFD PFI engine simulation. A preliminary assessment of the wall-film and droplet-wall interaction sub models has been carried out in order to validate the methodology. Then a three-step numerical procedure has been adopted. The first two steps are aimed to properly initialize the secondary breakup model depending on the type of injector installed on board in order to achieve accurate predictions of spray characteristics.

This paper presents a complete numerical and experimental characterisation of the transient diesel spray of a modern 5-holes high pressure electronic controlled injector performed in a constant volume pressurised vessel. The experimental analysis has been carried out using a self-developed injection rate measuring device, a visualisation rig based on a Nd-Yag pulsed laser and a synchronized CCD camera to measure spray penetration and spray cone angles and a PDA equipment to measure droplets size and velocity. The numerical analysis has been carried out by statically coupling a 1D model of the common rail injection system to a full 3D computation of both gas and fuel spray dynamics. The 1D injection system model has been developed in the AVL HYDSIM environment and the reliability of the model is demonstrated by comparing the numerical results with the experimental data. The multidimensional numerical simulation tool is a modified version of the KIVA-3V code.